diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c45e92202..5d5bd91b6 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -30,7 +30,7 @@ jobs:
       BOTO_CONFIG: /dev/null
       GO111MODULE: "on"
       GOPROXY: "https://proxy.golang.org"
-      GOVER: '1.21'
+      GOVER: '1.19'
 
     steps:
       - name: Checkout repository
@@ -99,7 +99,7 @@ jobs:
           - name: Ubuntu-20
             image: "ubuntu:20.04"
             suite: focal
-            GOVER: '1.21'
+            GOVER: '1.19'
             install: "make ca-certificates git curl"
           - name: Ubuntu-22
             image: "ubuntu:22.04"
@@ -108,12 +108,12 @@ jobs:
           - name: Debian-10
             image: "debian:buster"
             suite: buster
-            GOVER: '1.21'
+            GOVER: '1.19'
             install: "make ca-certificates git curl"
           - name: Debian-11
             image: "debian:bullseye"
             suite: bullseye
-            GOVER: '1.21'
+            GOVER: '1.19'
             install: "make ca-certificates git curl"
           - name: Debian-12
             image: "debian:bookworm"
diff --git a/api/api.go b/api/api.go
index ed46e457f..f27967422 100644
--- a/api/api.go
+++ b/api/api.go
@@ -189,7 +189,7 @@ func maybeRunTaskInBackground(c *gin.Context, name string, resources []string, p
 
 // Common piece of code to show list of packages,
 // with searching & details if requested
-func showPackages(c *gin.Context, reflist *deb.PackageRefList, collectionFactory *deb.CollectionFactory) {
+func showPackages(c *gin.Context, reflist deb.AnyRefList, collectionFactory *deb.CollectionFactory) {
 	result := []*deb.Package{}
 
 	list, err := deb.NewPackageListFromRefList(reflist, collectionFactory.PackageCollection(), nil)
diff --git a/api/db.go b/api/db.go
index 3f8b826dd..8869fbd99 100644
--- a/api/db.go
+++ b/api/db.go
@@ -5,6 +5,7 @@ import (
 	"sort"
 
 	"github.com/aptly-dev/aptly/aptly"
+	"github.com/aptly-dev/aptly/database"
 	"github.com/aptly-dev/aptly/deb"
 	"github.com/aptly-dev/aptly/task"
 	"github.com/aptly-dev/aptly/utils"
@@ -20,18 +21,22 @@ func apiDbCleanup(c *gin.Context) {
 
 		collectionFactory := context.NewCollectionFactory()
 
-		// collect information about referenced packages...
-		existingPackageRefs := deb.NewPackageRefList()
+		// collect information about referenced packages and their reflist buckets...
+		existingPackageRefs := deb.NewSplitRefList()
+		existingBuckets := deb.NewRefListDigestSet()
+
+		reflistMigration := collectionFactory.RefListCollection().NewMigration()
 
 		out.Printf("Loading mirrors, local repos, snapshots and published repos...")
 		err = collectionFactory.RemoteRepoCollection().ForEach(func(repo *deb.RemoteRepo) error {
-			e := collectionFactory.RemoteRepoCollection().LoadComplete(repo)
-			if e != nil {
+			sl := deb.NewSplitRefList()
+			e := collectionFactory.RefListCollection().LoadCompleteAndMigrate(sl, repo.RefKey(), reflistMigration)
+			if e != nil && e != database.ErrNotFound {
 				return e
 			}
-			if repo.RefList() != nil {
-				existingPackageRefs = existingPackageRefs.Merge(repo.RefList(), false, true)
-			}
+
+			existingPackageRefs = existingPackageRefs.Merge(sl, false, true)
+			existingBuckets.AddAllInRefList(sl)
 
 			return nil
 		})
@@ -40,14 +45,14 @@ func apiDbCleanup(c *gin.Context) {
 		}
 
 		err = collectionFactory.LocalRepoCollection().ForEach(func(repo *deb.LocalRepo) error {
-			e := collectionFactory.LocalRepoCollection().LoadComplete(repo)
-			if e != nil {
+			sl := deb.NewSplitRefList()
+			e := collectionFactory.RefListCollection().LoadCompleteAndMigrate(sl, repo.RefKey(), reflistMigration)
+			if e != nil && e != database.ErrNotFound {
 				return e
 			}
 
-			if repo.RefList() != nil {
-				existingPackageRefs = existingPackageRefs.Merge(repo.RefList(), false, true)
-			}
+			existingPackageRefs = existingPackageRefs.Merge(sl, false, true)
+			existingBuckets.AddAllInRefList(sl)
 
 			return nil
 		})
@@ -56,12 +61,14 @@ func apiDbCleanup(c *gin.Context) {
 		}
 
 		err = collectionFactory.SnapshotCollection().ForEach(func(snapshot *deb.Snapshot) error {
-			e := collectionFactory.SnapshotCollection().LoadComplete(snapshot)
+			sl := deb.NewSplitRefList()
+			e := collectionFactory.RefListCollection().LoadCompleteAndMigrate(sl, snapshot.RefKey(), reflistMigration)
 			if e != nil {
 				return e
 			}
 
-			existingPackageRefs = existingPackageRefs.Merge(snapshot.RefList(), false, true)
+			existingPackageRefs = existingPackageRefs.Merge(sl, false, true)
+			existingBuckets.AddAllInRefList(sl)
 
 			return nil
 		})
@@ -73,13 +80,16 @@ func apiDbCleanup(c *gin.Context) {
 			if published.SourceKind != deb.SourceLocalRepo {
 				return nil
 			}
-			e := collectionFactory.PublishedRepoCollection().LoadComplete(published, collectionFactory)
-			if e != nil {
-				return e
-			}
 
 			for _, component := range published.Components() {
-				existingPackageRefs = existingPackageRefs.Merge(published.RefList(component), false, true)
+				sl := deb.NewSplitRefList()
+				e := collectionFactory.RefListCollection().LoadCompleteAndMigrate(sl, published.RefKey(component), reflistMigration)
+				if e != nil {
+					return e
+				}
+
+				existingPackageRefs = existingPackageRefs.Merge(sl, false, true)
+				existingBuckets.AddAllInRefList(sl)
 			}
 			return nil
 		})
@@ -87,11 +97,20 @@ func apiDbCleanup(c *gin.Context) {
 			return nil, err
 		}
 
+		err = reflistMigration.Flush()
+		if err != nil {
+			return nil, err
+		}
+		if stats := reflistMigration.Stats(); stats.Reflists > 0 {
+			out.Printf("Split %d reflist(s) into %d bucket(s) (%d segment(s))",
+				stats.Reflists, stats.Buckets, stats.Segments)
+		}
+
 		// ... and compare it to the list of all packages
 		out.Printf("Loading list of all packages...")
 		allPackageRefs := collectionFactory.PackageCollection().AllPackageRefs()
 
-		toDelete := allPackageRefs.Subtract(existingPackageRefs)
+		toDelete := allPackageRefs.Subtract(existingPackageRefs.Flatten())
 
 		// delete packages that are no longer referenced
 		out.Printf("Deleting unreferenced packages (%d)...", toDelete.Len())
@@ -112,6 +131,28 @@ func apiDbCleanup(c *gin.Context) {
 			}
 		}
 
+		bucketsToDelete, err := collectionFactory.RefListCollection().AllBucketDigests()
+		if err != nil {
+			return nil, err
+		}
+
+		bucketsToDelete.RemoveAll(existingBuckets)
+
+		out.Printf("Deleting unreferenced reflist buckets (%d)...", bucketsToDelete.Len())
+		if bucketsToDelete.Len() > 0 {
+			batch := db.CreateBatch()
+			err := bucketsToDelete.ForEach(func(digest []byte) error {
+				return collectionFactory.RefListCollection().UnsafeDropBucket(digest, batch)
+			})
+			if err != nil {
+				return nil, err
+			}
+
+			if err := batch.Write(); err != nil {
+				return nil, err
+			}
+		}
+
 		// now, build a list of files that should be present in Repository (package pool)
 		out.Printf("Building list of files referenced by packages...")
 		referencedFiles := make([]string, 0, existingPackageRefs.Len())
diff --git a/api/files.go b/api/files.go
index 745d41c80..d4383e0e1 100644
--- a/api/files.go
+++ b/api/files.go
@@ -125,11 +125,7 @@ func apiFilesListFiles(c *gin.Context) {
 	listLock := &sync.Mutex{}
 	root := filepath.Join(context.UploadPath(), c.Params.ByName("dir"))
 
-	err := filepath.Walk(root, func(path string, _ os.FileInfo, err error) error {
-		if err != nil {
-			return err
-		}
-
+	err := walker.Walk(root, func(path string, _ os.FileInfo) error {
 		if path == root {
 			return nil
 		}
diff --git a/api/metrics.go b/api/metrics.go
index 94a9dc252..875c3c196 100644
--- a/api/metrics.go
+++ b/api/metrics.go
@@ -102,7 +102,7 @@ func countPackagesByRepos() {
 
 		components := repo.Components()
 		for _, c := range components {
-			count := float64(len(repo.RefList(c).Refs))
+			count := float64(repo.RefList(c).Len())
 			apiReposPackageCountGauge.WithLabelValues(fmt.Sprintf("%s", (repo.SourceNames())), repo.Distribution, c).Set(count)
 		}
 
diff --git a/api/mirror.go b/api/mirror.go
index 1d03f1efd..1a2992be9 100644
--- a/api/mirror.go
+++ b/api/mirror.go
@@ -124,7 +124,7 @@ func apiMirrorsCreate(c *gin.Context) {
 		return
 	}
 
-	err = collection.Add(repo)
+	err = collection.Add(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		AbortWithJSONError(c, 500, fmt.Errorf("unable to add mirror: %s", err))
 		return
@@ -184,7 +184,7 @@ func apiMirrorsShow(c *gin.Context) {
 		return
 	}
 
-	err = collection.LoadComplete(repo)
+	err = collection.LoadComplete(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		AbortWithJSONError(c, 500, fmt.Errorf("unable to show: %s", err))
 	}
@@ -204,7 +204,7 @@ func apiMirrorsPackages(c *gin.Context) {
 		return
 	}
 
-	err = collection.LoadComplete(repo)
+	err = collection.LoadComplete(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		AbortWithJSONError(c, 500, fmt.Errorf("unable to show: %s", err))
 	}
@@ -402,12 +402,12 @@ func apiMirrorsUpdate(c *gin.Context) {
 			e := context.ReOpenDatabase()
 			if e == nil {
 				remote.MarkAsIdle()
-				collection.Update(remote)
+				collection.Update(remote, collectionFactory.RefListCollection())
 			}
 		}()
 
 		remote.MarkAsUpdating()
-		err = collection.Update(remote)
+		err = collection.Update(remote, collectionFactory.RefListCollection())
 		if err != nil {
 			return &task.ProcessReturnValue{Code: http.StatusInternalServerError, Value: nil}, fmt.Errorf("unable to update: %s", err)
 		}
@@ -565,7 +565,7 @@ func apiMirrorsUpdate(c *gin.Context) {
 
 		log.Info().Msgf("%s: Finalizing download...", b.Name)
 		remote.FinalizeDownload(collectionFactory, out)
-		err = collectionFactory.RemoteRepoCollection().Update(remote)
+		err = collectionFactory.RemoteRepoCollection().Update(remote, collectionFactory.RefListCollection())
 		if err != nil {
 			return &task.ProcessReturnValue{Code: http.StatusInternalServerError, Value: nil}, fmt.Errorf("unable to update: %s", err)
 		}
diff --git a/api/publish.go b/api/publish.go
index adce3c84e..85bf68170 100644
--- a/api/publish.go
+++ b/api/publish.go
@@ -141,7 +141,7 @@ func apiPublishRepoOrSnapshot(c *gin.Context) {
 			}
 
 			resources = append(resources, string(snapshot.ResourceKey()))
-			err = snapshotCollection.LoadComplete(snapshot)
+			err = snapshotCollection.LoadComplete(snapshot, collectionFactory.RefListCollection())
 			if err != nil {
 				AbortWithJSONError(c, 500, fmt.Errorf("unable to publish: %s", err))
 				return
@@ -165,7 +165,7 @@ func apiPublishRepoOrSnapshot(c *gin.Context) {
 			}
 
 			resources = append(resources, string(localRepo.Key()))
-			err = localCollection.LoadComplete(localRepo)
+			err = localCollection.LoadComplete(localRepo, collectionFactory.RefListCollection())
 			if err != nil {
 				AbortWithJSONError(c, 500, fmt.Errorf("unable to publish: %s", err))
 			}
@@ -232,7 +232,7 @@ func apiPublishRepoOrSnapshot(c *gin.Context) {
 			return &task.ProcessReturnValue{Code: http.StatusInternalServerError, Value: nil}, fmt.Errorf("unable to publish: %s", err)
 		}
 
-		err = collection.Add(published)
+		err = collection.Add(published, collectionFactory.RefListCollection())
 		if err != nil {
 			return &task.ProcessReturnValue{Code: http.StatusInternalServerError, Value: nil}, fmt.Errorf("unable to save to DB: %s", err)
 		}
@@ -313,7 +313,7 @@ func apiPublishUpdateSwitch(c *gin.Context) {
 				return
 			}
 
-			err2 = snapshotCollection.LoadComplete(snapshot)
+			err2 = snapshotCollection.LoadComplete(snapshot, collectionFactory.RefListCollection())
 			if err2 != nil {
 				AbortWithJSONError(c, 500, err2)
 				return
@@ -348,7 +348,7 @@ func apiPublishUpdateSwitch(c *gin.Context) {
 			return &task.ProcessReturnValue{Code: http.StatusInternalServerError, Value: nil}, fmt.Errorf("unable to update: %s", err)
 		}
 
-		err = collection.Update(published)
+		err = collection.Update(published, collectionFactory.RefListCollection())
 		if err != nil {
 			return &task.ProcessReturnValue{Code: http.StatusInternalServerError, Value: nil}, fmt.Errorf("unable to save to DB: %s", err)
 		}
diff --git a/api/repos.go b/api/repos.go
index 6f7d435cd..ddd31c9fd 100644
--- a/api/repos.go
+++ b/api/repos.go
@@ -82,7 +82,7 @@ func apiReposCreate(c *gin.Context) {
 
 	collectionFactory := context.NewCollectionFactory()
 	collection := collectionFactory.LocalRepoCollection()
-	err := collection.Add(repo)
+	err := collection.Add(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		AbortWithJSONError(c, 400, err)
 		return
@@ -132,7 +132,7 @@ func apiReposEdit(c *gin.Context) {
 		repo.DefaultComponent = *b.DefaultComponent
 	}
 
-	err = collection.Update(repo)
+	err = collection.Update(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		AbortWithJSONError(c, 500, err)
 		return
@@ -201,7 +201,7 @@ func apiReposPackagesShow(c *gin.Context) {
 		return
 	}
 
-	err = collection.LoadComplete(repo)
+	err = collection.LoadComplete(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		AbortWithJSONError(c, 500, err)
 		return
@@ -229,7 +229,7 @@ func apiReposPackagesAddDelete(c *gin.Context, taskNamePrefix string, cb func(li
 		return
 	}
 
-	err = collection.LoadComplete(repo)
+	err = collection.LoadComplete(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		AbortWithJSONError(c, 500, err)
 		return
@@ -261,9 +261,9 @@ func apiReposPackagesAddDelete(c *gin.Context, taskNamePrefix string, cb func(li
 			}
 		}
 
-		repo.UpdateRefList(deb.NewPackageRefListFromPackageList(list))
+		repo.UpdateRefList(deb.NewSplitRefListFromPackageList(list))
 
-		err = collectionFactory.LocalRepoCollection().Update(repo)
+		err = collectionFactory.LocalRepoCollection().Update(repo, collectionFactory.RefListCollection())
 		if err != nil {
 			return &task.ProcessReturnValue{Code: http.StatusInternalServerError, Value: nil}, fmt.Errorf("unable to save: %s", err)
 		}
@@ -320,7 +320,7 @@ func apiReposPackageFromDir(c *gin.Context) {
 		return
 	}
 
-	err = collection.LoadComplete(repo)
+	err = collection.LoadComplete(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		AbortWithJSONError(c, 500, err)
 		return
@@ -369,9 +369,9 @@ func apiReposPackageFromDir(c *gin.Context) {
 			return &task.ProcessReturnValue{Code: http.StatusInternalServerError, Value: nil}, fmt.Errorf("unable to import package files: %s", err)
 		}
 
-		repo.UpdateRefList(deb.NewPackageRefListFromPackageList(list))
+		repo.UpdateRefList(deb.NewSplitRefListFromPackageList(list))
 
-		err = collectionFactory.LocalRepoCollection().Update(repo)
+		err = collectionFactory.LocalRepoCollection().Update(repo, collectionFactory.RefListCollection())
 		if err != nil {
 			return &task.ProcessReturnValue{Code: http.StatusInternalServerError, Value: nil}, fmt.Errorf("unable to save: %s", err)
 		}
@@ -489,7 +489,7 @@ func apiReposIncludePackageFromDir(c *gin.Context) {
 		_, failedFiles2, err = deb.ImportChangesFiles(
 			changesFiles, reporter, acceptUnsigned, ignoreSignature, forceReplace, noRemoveFiles, verifier,
 			repoTemplate, context.Progress(), collectionFactory.LocalRepoCollection(), collectionFactory.PackageCollection(),
-			context.PackagePool(), collectionFactory.ChecksumCollection, nil, query.Parse)
+			collectionFactory.RefListCollection(), context.PackagePool(), collectionFactory.ChecksumCollection, nil, query.Parse)
 		failedFiles = append(failedFiles, failedFiles2...)
 
 		if err != nil {
diff --git a/api/snapshot.go b/api/snapshot.go
index dfad75c34..eeb5bb32f 100644
--- a/api/snapshot.go
+++ b/api/snapshot.go
@@ -69,7 +69,7 @@ func apiSnapshotsCreateFromMirror(c *gin.Context) {
 			return &task.ProcessReturnValue{Code: http.StatusConflict, Value: nil}, err
 		}
 
-		err = collection.LoadComplete(repo)
+		err = collection.LoadComplete(repo, collectionFactory.RefListCollection())
 		if err != nil {
 			return &task.ProcessReturnValue{Code: http.StatusInternalServerError, Value: nil}, err
 		}
@@ -83,7 +83,7 @@ func apiSnapshotsCreateFromMirror(c *gin.Context) {
 			snapshot.Description = b.Description
 		}
 
-		err = snapshotCollection.Add(snapshot)
+		err = snapshotCollection.Add(snapshot, collectionFactory.RefListCollection())
 		if err != nil {
 			return &task.ProcessReturnValue{Code: http.StatusBadRequest, Value: nil}, err
 		}
@@ -128,7 +128,7 @@ func apiSnapshotsCreate(c *gin.Context) {
 			return
 		}
 
-		err = snapshotCollection.LoadComplete(sources[i])
+		err = snapshotCollection.LoadComplete(sources[i], collectionFactory.RefListCollection())
 		if err != nil {
 			AbortWithJSONError(c, 500, err)
 			return
@@ -155,9 +155,9 @@ func apiSnapshotsCreate(c *gin.Context) {
 			}
 		}
 
-		snapshot = deb.NewSnapshotFromRefList(b.Name, sources, deb.NewPackageRefListFromPackageList(list), b.Description)
+		snapshot = deb.NewSnapshotFromRefList(b.Name, sources, deb.NewSplitRefListFromPackageList(list), b.Description)
 
-		err = snapshotCollection.Add(snapshot)
+		err = snapshotCollection.Add(snapshot, collectionFactory.RefListCollection())
 		if err != nil {
 			return &task.ProcessReturnValue{Code: http.StatusBadRequest, Value: nil}, err
 		}
@@ -197,7 +197,7 @@ func apiSnapshotsCreateFromRepository(c *gin.Context) {
 	resources := []string{string(repo.Key()), "S" + b.Name}
 	taskName := fmt.Sprintf("Create snapshot of repo %s", name)
 	maybeRunTaskInBackground(c, taskName, resources, func(_ aptly.Progress, _ *task.Detail) (*task.ProcessReturnValue, error) {
-		err := collection.LoadComplete(repo)
+		err := collection.LoadComplete(repo, collectionFactory.RefListCollection())
 		if err != nil {
 			return &task.ProcessReturnValue{Code: http.StatusInternalServerError, Value: nil}, err
 		}
@@ -211,7 +211,7 @@ func apiSnapshotsCreateFromRepository(c *gin.Context) {
 			snapshot.Description = b.Description
 		}
 
-		err = snapshotCollection.Add(snapshot)
+		err = snapshotCollection.Add(snapshot, collectionFactory.RefListCollection())
 		if err != nil {
 			return &task.ProcessReturnValue{Code: http.StatusBadRequest, Value: nil}, err
 		}
@@ -261,7 +261,7 @@ func apiSnapshotsUpdate(c *gin.Context) {
 			snapshot.Description = b.Description
 		}
 
-		err = collectionFactory.SnapshotCollection().Update(snapshot)
+		err = collectionFactory.SnapshotCollection().Update(snapshot, collectionFactory.RefListCollection())
 		if err != nil {
 			return &task.ProcessReturnValue{Code: http.StatusInternalServerError, Value: nil}, err
 		}
@@ -280,7 +280,7 @@ func apiSnapshotsShow(c *gin.Context) {
 		return
 	}
 
-	err = collection.LoadComplete(snapshot)
+	err = collection.LoadComplete(snapshot, collectionFactory.RefListCollection())
 	if err != nil {
 		AbortWithJSONError(c, 500, err)
 		return
@@ -347,20 +347,20 @@ func apiSnapshotsDiff(c *gin.Context) {
 		return
 	}
 
-	err = collection.LoadComplete(snapshotA)
+	err = collection.LoadComplete(snapshotA, collectionFactory.RefListCollection())
 	if err != nil {
 		AbortWithJSONError(c, 500, err)
 		return
 	}
 
-	err = collection.LoadComplete(snapshotB)
+	err = collection.LoadComplete(snapshotB, collectionFactory.RefListCollection())
 	if err != nil {
 		AbortWithJSONError(c, 500, err)
 		return
 	}
 
 	// Calculate diff
-	diff, err := snapshotA.RefList().Diff(snapshotB.RefList(), collectionFactory.PackageCollection())
+	diff, err := snapshotA.RefList().Diff(snapshotB.RefList(), collectionFactory.PackageCollection(), nil)
 	if err != nil {
 		AbortWithJSONError(c, 500, err)
 		return
@@ -390,7 +390,7 @@ func apiSnapshotsSearchPackages(c *gin.Context) {
 		return
 	}
 
-	err = collection.LoadComplete(snapshot)
+	err = collection.LoadComplete(snapshot, collectionFactory.RefListCollection())
 	if err != nil {
 		AbortWithJSONError(c, 500, err)
 		return
@@ -441,7 +441,7 @@ func apiSnapshotsMerge(c *gin.Context) {
 			return
 		}
 
-		err = snapshotCollection.LoadComplete(sources[i])
+		err = snapshotCollection.LoadComplete(sources[i], collectionFactory.RefListCollection())
 		if err != nil {
 			AbortWithJSONError(c, http.StatusInternalServerError, err)
 			return
@@ -467,7 +467,7 @@ func apiSnapshotsMerge(c *gin.Context) {
 		snapshot = deb.NewSnapshotFromRefList(body.Destination, sources, result,
 			fmt.Sprintf("Merged from sources: %s", strings.Join(sourceDescription, ", ")))
 
-		err = collectionFactory.SnapshotCollection().Add(snapshot)
+		err = collectionFactory.SnapshotCollection().Add(snapshot, collectionFactory.RefListCollection())
 		if err != nil {
 			return &task.ProcessReturnValue{Code: http.StatusInternalServerError, Value: nil}, fmt.Errorf("unable to create snapshot: %s", err)
 		}
diff --git a/cmd/cmd.go b/cmd/cmd.go
index 14a0efd16..b70bf145c 100644
--- a/cmd/cmd.go
+++ b/cmd/cmd.go
@@ -21,7 +21,7 @@ const (
 )
 
 // ListPackagesRefList shows list of packages in PackageRefList
-func ListPackagesRefList(reflist *deb.PackageRefList, collectionFactory *deb.CollectionFactory) (err error) {
+func ListPackagesRefList(reflist deb.AnyRefList, collectionFactory *deb.CollectionFactory) (err error) {
 	fmt.Printf("Packages:\n")
 
 	if reflist == nil {
diff --git a/cmd/db_cleanup.go b/cmd/db_cleanup.go
index 66fece677..ec1906859 100644
--- a/cmd/db_cleanup.go
+++ b/cmd/db_cleanup.go
@@ -6,6 +6,7 @@ import (
 	"strings"
 
 	"github.com/aptly-dev/aptly/aptly"
+	"github.com/aptly-dev/aptly/database"
 	"github.com/aptly-dev/aptly/deb"
 	"github.com/aptly-dev/aptly/utils"
 	"github.com/smira/commander"
@@ -24,12 +25,20 @@ func aptlyDbCleanup(cmd *commander.Command, args []string) error {
 	dryRun := context.Flags().Lookup("dry-run").Value.Get().(bool)
 	collectionFactory := context.NewCollectionFactory()
 
-	// collect information about references packages...
-	existingPackageRefs := deb.NewPackageRefList()
+	// collect information about references packages and their reflistbuckets...
+	existingPackageRefs := deb.NewSplitRefList()
+	existingBuckets := deb.NewRefListDigestSet()
 
 	// used only in verbose mode to report package use source
 	packageRefSources := map[string][]string{}
 
+	var reflistMigration *deb.RefListMigration
+	if !dryRun {
+		reflistMigration = collectionFactory.RefListCollection().NewMigration()
+	} else {
+		reflistMigration = collectionFactory.RefListCollection().NewMigrationDryRun()
+	}
+
 	context.Progress().ColoredPrintf("@{w!}Loading mirrors, local repos, snapshots and published repos...@|")
 	if verbose {
 		context.Progress().ColoredPrintf("@{y}Loading mirrors:@|")
@@ -39,20 +48,21 @@ func aptlyDbCleanup(cmd *commander.Command, args []string) error {
 			context.Progress().ColoredPrintf("- @{g}%s@|", repo.Name)
 		}
 
-		e := collectionFactory.RemoteRepoCollection().LoadComplete(repo)
-		if e != nil {
+		sl := deb.NewSplitRefList()
+		e := collectionFactory.RefListCollection().LoadCompleteAndMigrate(sl, repo.RefKey(), reflistMigration)
+		if e != nil && e != database.ErrNotFound {
 			return e
 		}
-		if repo.RefList() != nil {
-			existingPackageRefs = existingPackageRefs.Merge(repo.RefList(), false, true)
 
-			if verbose {
-				description := fmt.Sprintf("mirror %s", repo.Name)
-				repo.RefList().ForEach(func(key []byte) error {
-					packageRefSources[string(key)] = append(packageRefSources[string(key)], description)
-					return nil
-				})
-			}
+		existingPackageRefs = existingPackageRefs.Merge(sl, false, true)
+		existingBuckets.AddAllInRefList(sl)
+
+		if verbose {
+			description := fmt.Sprintf("mirror %s", repo.Name)
+			sl.ForEach(func(key []byte) error {
+				packageRefSources[string(key)] = append(packageRefSources[string(key)], description)
+				return nil
+			})
 		}
 
 		return nil
@@ -71,21 +81,23 @@ func aptlyDbCleanup(cmd *commander.Command, args []string) error {
 			context.Progress().ColoredPrintf("- @{g}%s@|", repo.Name)
 		}
 
-		e := collectionFactory.LocalRepoCollection().LoadComplete(repo)
-		if e != nil {
+		sl := deb.NewSplitRefList()
+		e := collectionFactory.RefListCollection().LoadCompleteAndMigrate(sl, repo.RefKey(), reflistMigration)
+		if e != nil && e != database.ErrNotFound {
 			return e
 		}
 
-		if repo.RefList() != nil {
-			existingPackageRefs = existingPackageRefs.Merge(repo.RefList(), false, true)
+		existingPackageRefs = existingPackageRefs.Merge(sl, false, true)
+		existingBuckets.AddAllInRefList(sl)
 
-			if verbose {
-				description := fmt.Sprintf("local repo %s", repo.Name)
-				repo.RefList().ForEach(func(key []byte) error {
-					packageRefSources[string(key)] = append(packageRefSources[string(key)], description)
-					return nil
-				})
-			}
+		existingPackageRefs = existingPackageRefs.Merge(sl, false, true)
+
+		if verbose {
+			description := fmt.Sprintf("local repo %s", repo.Name)
+			sl.ForEach(func(key []byte) error {
+				packageRefSources[string(key)] = append(packageRefSources[string(key)], description)
+				return nil
+			})
 		}
 
 		return nil
@@ -104,16 +116,18 @@ func aptlyDbCleanup(cmd *commander.Command, args []string) error {
 			context.Progress().ColoredPrintf("- @{g}%s@|", snapshot.Name)
 		}
 
-		e := collectionFactory.SnapshotCollection().LoadComplete(snapshot)
+		sl := deb.NewSplitRefList()
+		e := collectionFactory.RefListCollection().LoadCompleteAndMigrate(sl, snapshot.RefKey(), reflistMigration)
 		if e != nil {
 			return e
 		}
 
-		existingPackageRefs = existingPackageRefs.Merge(snapshot.RefList(), false, true)
+		existingPackageRefs = existingPackageRefs.Merge(sl, false, true)
+		existingBuckets.AddAllInRefList(sl)
 
 		if verbose {
 			description := fmt.Sprintf("snapshot %s", snapshot.Name)
-			snapshot.RefList().ForEach(func(key []byte) error {
+			sl.ForEach(func(key []byte) error {
 				packageRefSources[string(key)] = append(packageRefSources[string(key)], description)
 				return nil
 			})
@@ -136,17 +150,21 @@ func aptlyDbCleanup(cmd *commander.Command, args []string) error {
 		if published.SourceKind != deb.SourceLocalRepo {
 			return nil
 		}
-		e := collectionFactory.PublishedRepoCollection().LoadComplete(published, collectionFactory)
-		if e != nil {
-			return e
-		}
 
 		for _, component := range published.Components() {
-			existingPackageRefs = existingPackageRefs.Merge(published.RefList(component), false, true)
+			sl := deb.NewSplitRefList()
+			e := collectionFactory.RefListCollection().LoadCompleteAndMigrate(sl, published.RefKey(component), reflistMigration)
+			if e != nil {
+				return e
+			}
+
+			existingPackageRefs = existingPackageRefs.Merge(sl, false, true)
+			existingBuckets.AddAllInRefList(sl)
+
 			if verbose {
 				description := fmt.Sprintf("published repository %s:%s/%s component %s",
 					published.Storage, published.Prefix, published.Distribution, component)
-				published.RefList(component).ForEach(func(key []byte) error {
+				sl.ForEach(func(key []byte) error {
 					packageRefSources[string(key)] = append(packageRefSources[string(key)], description)
 					return nil
 				})
@@ -160,11 +178,29 @@ func aptlyDbCleanup(cmd *commander.Command, args []string) error {
 
 	collectionFactory.Flush()
 
+	err = reflistMigration.Flush()
+	if err != nil {
+		return err
+	}
+
+	if verbose {
+		if stats := reflistMigration.Stats(); stats.Reflists > 0 {
+			if !dryRun {
+				context.Progress().ColoredPrintf("@{w!}Split %d reflist(s) into %d bucket(s) (%d segment(s))@|",
+					stats.Reflists, stats.Buckets, stats.Segments)
+			} else {
+				context.Progress().ColoredPrintf(
+					"@{y!}Skipped splitting %d reflist(s) into %d bucket(s) (%d segment(s)), as -dry-run has been requested.@|",
+					stats.Reflists, stats.Buckets, stats.Segments)
+			}
+		}
+	}
+
 	// ... and compare it to the list of all packages
 	context.Progress().ColoredPrintf("@{w!}Loading list of all packages...@|")
 	allPackageRefs := collectionFactory.PackageCollection().AllPackageRefs()
 
-	toDelete := allPackageRefs.Subtract(existingPackageRefs)
+	toDelete := allPackageRefs.Subtract(existingPackageRefs.Flatten())
 
 	// delete packages that are no longer referenced
 	context.Progress().ColoredPrintf("@{r!}Deleting unreferenced packages (%d)...@|", toDelete.Len())
@@ -202,6 +238,32 @@ func aptlyDbCleanup(cmd *commander.Command, args []string) error {
 		}
 	}
 
+	bucketsToDelete, err := collectionFactory.RefListCollection().AllBucketDigests()
+	if err != nil {
+		return err
+	}
+
+	bucketsToDelete.RemoveAll(existingBuckets)
+
+	context.Progress().ColoredPrintf("@{r!}Deleting unreferenced reflist buckets (%d)...@|", bucketsToDelete.Len())
+	if bucketsToDelete.Len() > 0 {
+		if !dryRun {
+			batch := db.CreateBatch()
+			err := bucketsToDelete.ForEach(func(digest []byte) error {
+				return collectionFactory.RefListCollection().UnsafeDropBucket(digest, batch)
+			})
+			if err != nil {
+				return err
+			}
+
+			if err := batch.Write(); err != nil {
+				return err
+			}
+		} else {
+			context.Progress().ColoredPrintf("@{y!}Skipped reflist deletion, as -dry-run has been requested.@|")
+		}
+	}
+
 	collectionFactory.Flush()
 
 	// now, build a list of files that should be present in Repository (package pool)
diff --git a/cmd/mirror_create.go b/cmd/mirror_create.go
index 78d91b582..eb2ba7cab 100644
--- a/cmd/mirror_create.go
+++ b/cmd/mirror_create.go
@@ -65,7 +65,7 @@ func aptlyMirrorCreate(cmd *commander.Command, args []string) error {
 	}
 
 	collectionFactory := context.NewCollectionFactory()
-	err = collectionFactory.RemoteRepoCollection().Add(repo)
+	err = collectionFactory.RemoteRepoCollection().Add(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to add mirror: %s", err)
 	}
diff --git a/cmd/mirror_edit.go b/cmd/mirror_edit.go
index 86462c4c0..93986c062 100644
--- a/cmd/mirror_edit.go
+++ b/cmd/mirror_edit.go
@@ -75,7 +75,7 @@ func aptlyMirrorEdit(cmd *commander.Command, args []string) error {
 		}
 	}
 
-	err = collectionFactory.RemoteRepoCollection().Update(repo)
+	err = collectionFactory.RemoteRepoCollection().Update(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to edit: %s", err)
 	}
diff --git a/cmd/mirror_rename.go b/cmd/mirror_rename.go
index 2ff9f9204..ff453b857 100644
--- a/cmd/mirror_rename.go
+++ b/cmd/mirror_rename.go
@@ -37,7 +37,7 @@ func aptlyMirrorRename(cmd *commander.Command, args []string) error {
 	}
 
 	repo.Name = newName
-	err = collectionFactory.RemoteRepoCollection().Update(repo)
+	err = collectionFactory.RemoteRepoCollection().Update(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to rename: %s", err)
 	}
diff --git a/cmd/mirror_show.go b/cmd/mirror_show.go
index 03179161a..3c52d6e37 100644
--- a/cmd/mirror_show.go
+++ b/cmd/mirror_show.go
@@ -38,7 +38,7 @@ func aptlyMirrorShowTxt(_ *commander.Command, args []string) error {
 		return fmt.Errorf("unable to show: %s", err)
 	}
 
-	err = collectionFactory.RemoteRepoCollection().LoadComplete(repo)
+	err = collectionFactory.RemoteRepoCollection().LoadComplete(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to show: %s", err)
 	}
@@ -98,12 +98,13 @@ func aptlyMirrorShowJSON(_ *commander.Command, args []string) error {
 
 	name := args[0]
 
-	repo, err := context.NewCollectionFactory().RemoteRepoCollection().ByName(name)
+	collectionFactory := context.NewCollectionFactory()
+	repo, err := collectionFactory.RemoteRepoCollection().ByName(name)
 	if err != nil {
 		return fmt.Errorf("unable to show: %s", err)
 	}
 
-	err = context.NewCollectionFactory().RemoteRepoCollection().LoadComplete(repo)
+	err = collectionFactory.RemoteRepoCollection().LoadComplete(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to show: %s", err)
 	}
@@ -113,7 +114,7 @@ func aptlyMirrorShowJSON(_ *commander.Command, args []string) error {
 	if withPackages {
 		if repo.RefList() != nil {
 			var list *deb.PackageList
-			list, err = deb.NewPackageListFromRefList(repo.RefList(), context.NewCollectionFactory().PackageCollection(), context.Progress())
+			list, err = deb.NewPackageListFromRefList(repo.RefList(), collectionFactory.PackageCollection(), context.Progress())
 			if err != nil {
 				return fmt.Errorf("unable to get package list: %s", err)
 			}
diff --git a/cmd/mirror_update.go b/cmd/mirror_update.go
index 541baced2..4b9e72149 100644
--- a/cmd/mirror_update.go
+++ b/cmd/mirror_update.go
@@ -29,7 +29,7 @@ func aptlyMirrorUpdate(cmd *commander.Command, args []string) error {
 		return fmt.Errorf("unable to update: %s", err)
 	}
 
-	err = collectionFactory.RemoteRepoCollection().LoadComplete(repo)
+	err = collectionFactory.RemoteRepoCollection().LoadComplete(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to update: %s", err)
 	}
@@ -97,12 +97,12 @@ func aptlyMirrorUpdate(cmd *commander.Command, args []string) error {
 		err = context.ReOpenDatabase()
 		if err == nil {
 			repo.MarkAsIdle()
-			collectionFactory.RemoteRepoCollection().Update(repo)
+			collectionFactory.RemoteRepoCollection().Update(repo, collectionFactory.RefListCollection())
 		}
 	}()
 
 	repo.MarkAsUpdating()
-	err = collectionFactory.RemoteRepoCollection().Update(repo)
+	err = collectionFactory.RemoteRepoCollection().Update(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to update: %s", err)
 	}
@@ -258,7 +258,7 @@ func aptlyMirrorUpdate(cmd *commander.Command, args []string) error {
 	}
 
 	repo.FinalizeDownload(collectionFactory, context.Progress())
-	err = collectionFactory.RemoteRepoCollection().Update(repo)
+	err = collectionFactory.RemoteRepoCollection().Update(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to update: %s", err)
 	}
diff --git a/cmd/package_show.go b/cmd/package_show.go
index 37f07e9b0..6bbec9849 100644
--- a/cmd/package_show.go
+++ b/cmd/package_show.go
@@ -14,7 +14,7 @@ import (
 
 func printReferencesTo(p *deb.Package, collectionFactory *deb.CollectionFactory) (err error) {
 	err = collectionFactory.RemoteRepoCollection().ForEach(func(repo *deb.RemoteRepo) error {
-		e := collectionFactory.RemoteRepoCollection().LoadComplete(repo)
+		e := collectionFactory.RemoteRepoCollection().LoadComplete(repo, collectionFactory.RefListCollection())
 		if e != nil {
 			return e
 		}
@@ -30,7 +30,7 @@ func printReferencesTo(p *deb.Package, collectionFactory *deb.CollectionFactory)
 	}
 
 	err = collectionFactory.LocalRepoCollection().ForEach(func(repo *deb.LocalRepo) error {
-		e := collectionFactory.LocalRepoCollection().LoadComplete(repo)
+		e := collectionFactory.LocalRepoCollection().LoadComplete(repo, collectionFactory.RefListCollection())
 		if e != nil {
 			return e
 		}
@@ -46,7 +46,7 @@ func printReferencesTo(p *deb.Package, collectionFactory *deb.CollectionFactory)
 	}
 
 	err = collectionFactory.SnapshotCollection().ForEach(func(snapshot *deb.Snapshot) error {
-		e := collectionFactory.SnapshotCollection().LoadComplete(snapshot)
+		e := collectionFactory.SnapshotCollection().LoadComplete(snapshot, collectionFactory.RefListCollection())
 		if e != nil {
 			return e
 		}
diff --git a/cmd/publish_snapshot.go b/cmd/publish_snapshot.go
index 1e79fac27..23ab59775 100644
--- a/cmd/publish_snapshot.go
+++ b/cmd/publish_snapshot.go
@@ -49,7 +49,7 @@ func aptlyPublishSnapshotOrRepo(cmd *commander.Command, args []string) error {
 				return fmt.Errorf("unable to publish: %s", err)
 			}
 
-			err = collectionFactory.SnapshotCollection().LoadComplete(snapshot)
+			err = collectionFactory.SnapshotCollection().LoadComplete(snapshot, collectionFactory.RefListCollection())
 			if err != nil {
 				return fmt.Errorf("unable to publish: %s", err)
 			}
@@ -85,7 +85,7 @@ func aptlyPublishSnapshotOrRepo(cmd *commander.Command, args []string) error {
 				return fmt.Errorf("unable to publish: %s", err)
 			}
 
-			err = collectionFactory.LocalRepoCollection().LoadComplete(localRepo)
+			err = collectionFactory.LocalRepoCollection().LoadComplete(localRepo, collectionFactory.RefListCollection())
 			if err != nil {
 				return fmt.Errorf("unable to publish: %s", err)
 			}
@@ -171,7 +171,7 @@ func aptlyPublishSnapshotOrRepo(cmd *commander.Command, args []string) error {
 		return fmt.Errorf("unable to publish: %s", err)
 	}
 
-	err = collectionFactory.PublishedRepoCollection().Add(published)
+	err = collectionFactory.PublishedRepoCollection().Add(published, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to save to DB: %s", err)
 	}
diff --git a/cmd/publish_switch.go b/cmd/publish_switch.go
index 58a1195cb..382423ba7 100644
--- a/cmd/publish_switch.go
+++ b/cmd/publish_switch.go
@@ -74,7 +74,7 @@ func aptlyPublishSwitch(cmd *commander.Command, args []string) error {
 			return fmt.Errorf("unable to switch: %s", err)
 		}
 
-		err = collectionFactory.SnapshotCollection().LoadComplete(snapshot)
+		err = collectionFactory.SnapshotCollection().LoadComplete(snapshot, collectionFactory.RefListCollection())
 		if err != nil {
 			return fmt.Errorf("unable to switch: %s", err)
 		}
@@ -106,7 +106,7 @@ func aptlyPublishSwitch(cmd *commander.Command, args []string) error {
 		return fmt.Errorf("unable to publish: %s", err)
 	}
 
-	err = collectionFactory.PublishedRepoCollection().Update(published)
+	err = collectionFactory.PublishedRepoCollection().Update(published, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to save to DB: %s", err)
 	}
diff --git a/cmd/publish_update.go b/cmd/publish_update.go
index 9bceda509..15eb4ce76 100644
--- a/cmd/publish_update.go
+++ b/cmd/publish_update.go
@@ -70,7 +70,7 @@ func aptlyPublishUpdate(cmd *commander.Command, args []string) error {
 		return fmt.Errorf("unable to publish: %s", err)
 	}
 
-	err = collectionFactory.PublishedRepoCollection().Update(published)
+	err = collectionFactory.PublishedRepoCollection().Update(published, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to save to DB: %s", err)
 	}
diff --git a/cmd/repo_add.go b/cmd/repo_add.go
index 8189e7834..0263879f3 100644
--- a/cmd/repo_add.go
+++ b/cmd/repo_add.go
@@ -28,7 +28,7 @@ func aptlyRepoAdd(cmd *commander.Command, args []string) error {
 		return fmt.Errorf("unable to add: %s", err)
 	}
 
-	err = collectionFactory.LocalRepoCollection().LoadComplete(repo)
+	err = collectionFactory.LocalRepoCollection().LoadComplete(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to add: %s", err)
 	}
@@ -58,9 +58,9 @@ func aptlyRepoAdd(cmd *commander.Command, args []string) error {
 
 	processedFiles = append(processedFiles, otherFiles...)
 
-	repo.UpdateRefList(deb.NewPackageRefListFromPackageList(list))
+	repo.UpdateRefList(deb.NewSplitRefListFromPackageList(list))
 
-	err = collectionFactory.LocalRepoCollection().Update(repo)
+	err = collectionFactory.LocalRepoCollection().Update(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to save: %s", err)
 	}
diff --git a/cmd/repo_create.go b/cmd/repo_create.go
index 5fef46d92..0e3a1e52b 100644
--- a/cmd/repo_create.go
+++ b/cmd/repo_create.go
@@ -36,7 +36,7 @@ func aptlyRepoCreate(cmd *commander.Command, args []string) error {
 			return fmt.Errorf("unable to load source snapshot: %s", err)
 		}
 
-		err = collectionFactory.SnapshotCollection().LoadComplete(snapshot)
+		err = collectionFactory.SnapshotCollection().LoadComplete(snapshot, collectionFactory.RefListCollection())
 		if err != nil {
 			return fmt.Errorf("unable to load source snapshot: %s", err)
 		}
@@ -44,7 +44,7 @@ func aptlyRepoCreate(cmd *commander.Command, args []string) error {
 		repo.UpdateRefList(snapshot.RefList())
 	}
 
-	err = collectionFactory.LocalRepoCollection().Add(repo)
+	err = collectionFactory.LocalRepoCollection().Add(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to add local repo: %s", err)
 	}
diff --git a/cmd/repo_edit.go b/cmd/repo_edit.go
index bc81dc4a1..c7fbc4196 100644
--- a/cmd/repo_edit.go
+++ b/cmd/repo_edit.go
@@ -22,7 +22,7 @@ func aptlyRepoEdit(cmd *commander.Command, args []string) error {
 		return fmt.Errorf("unable to edit: %s", err)
 	}
 
-	err = collectionFactory.LocalRepoCollection().LoadComplete(repo)
+	err = collectionFactory.LocalRepoCollection().LoadComplete(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to edit: %s", err)
 	}
@@ -53,7 +53,7 @@ func aptlyRepoEdit(cmd *commander.Command, args []string) error {
 		}
 	}
 
-	err = collectionFactory.LocalRepoCollection().Update(repo)
+	err = collectionFactory.LocalRepoCollection().Update(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to edit: %s", err)
 	}
diff --git a/cmd/repo_include.go b/cmd/repo_include.go
index b84b96a38..4a750db1f 100644
--- a/cmd/repo_include.go
+++ b/cmd/repo_include.go
@@ -64,7 +64,7 @@ func aptlyRepoInclude(cmd *commander.Command, args []string) error {
 	_, failedFiles2, err = deb.ImportChangesFiles(
 		changesFiles, reporter, acceptUnsigned, ignoreSignatures, forceReplace, noRemoveFiles, verifier, repoTemplate,
 		context.Progress(), collectionFactory.LocalRepoCollection(), collectionFactory.PackageCollection(),
-		context.PackagePool(), collectionFactory.ChecksumCollection,
+		collectionFactory.RefListCollection(), context.PackagePool(), collectionFactory.ChecksumCollection,
 		uploaders, query.Parse)
 	failedFiles = append(failedFiles, failedFiles2...)
 
diff --git a/cmd/repo_list.go b/cmd/repo_list.go
index 9c4b0d47e..f3ca4a8ba 100644
--- a/cmd/repo_list.go
+++ b/cmd/repo_list.go
@@ -36,7 +36,7 @@ func aptlyRepoListTxt(cmd *commander.Command, _ []string) error {
 		if raw {
 			repos[i] = repo.Name
 		} else {
-			e := collectionFactory.LocalRepoCollection().LoadComplete(repo)
+			e := collectionFactory.LocalRepoCollection().LoadComplete(repo, collectionFactory.RefListCollection())
 			if e != nil {
 				return e
 			}
@@ -77,7 +77,8 @@ func aptlyRepoListJSON(_ *commander.Command, _ []string) error {
 	repos := make([]*deb.LocalRepo, context.NewCollectionFactory().LocalRepoCollection().Len())
 	i := 0
 	context.NewCollectionFactory().LocalRepoCollection().ForEach(func(repo *deb.LocalRepo) error {
-		e := context.NewCollectionFactory().LocalRepoCollection().LoadComplete(repo)
+		collectionFactory := context.NewCollectionFactory()
+		e := collectionFactory.LocalRepoCollection().LoadComplete(repo, collectionFactory.RefListCollection())
 		if e != nil {
 			return e
 		}
diff --git a/cmd/repo_move.go b/cmd/repo_move.go
index 8be6698b6..a1c5ba261 100644
--- a/cmd/repo_move.go
+++ b/cmd/repo_move.go
@@ -25,13 +25,13 @@ func aptlyRepoMoveCopyImport(cmd *commander.Command, args []string) error {
 		return fmt.Errorf("unable to %s: %s", command, err)
 	}
 
-	err = collectionFactory.LocalRepoCollection().LoadComplete(dstRepo)
+	err = collectionFactory.LocalRepoCollection().LoadComplete(dstRepo, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to %s: %s", command, err)
 	}
 
 	var (
-		srcRefList *deb.PackageRefList
+		srcRefList *deb.SplitRefList
 		srcRepo    *deb.LocalRepo
 	)
 
@@ -45,7 +45,7 @@ func aptlyRepoMoveCopyImport(cmd *commander.Command, args []string) error {
 			return fmt.Errorf("unable to %s: source and destination are the same", command)
 		}
 
-		err = collectionFactory.LocalRepoCollection().LoadComplete(srcRepo)
+		err = collectionFactory.LocalRepoCollection().LoadComplete(srcRepo, collectionFactory.RefListCollection())
 		if err != nil {
 			return fmt.Errorf("unable to %s: %s", command, err)
 		}
@@ -59,12 +59,12 @@ func aptlyRepoMoveCopyImport(cmd *commander.Command, args []string) error {
 			return fmt.Errorf("unable to %s: %s", command, err)
 		}
 
-		err = collectionFactory.RemoteRepoCollection().LoadComplete(srcRemoteRepo)
+		err = collectionFactory.RemoteRepoCollection().LoadComplete(srcRemoteRepo, collectionFactory.RefListCollection())
 		if err != nil {
 			return fmt.Errorf("unable to %s: %s", command, err)
 		}
 
-		if srcRemoteRepo.RefList() == nil {
+		if srcRemoteRepo.RefList().Len() == 0 {
 			return fmt.Errorf("unable to %s: mirror not updated", command)
 		}
 
@@ -150,17 +150,17 @@ func aptlyRepoMoveCopyImport(cmd *commander.Command, args []string) error {
 	if context.Flags().Lookup("dry-run").Value.Get().(bool) {
 		context.Progress().Printf("\nChanges not saved, as dry run has been requested.\n")
 	} else {
-		dstRepo.UpdateRefList(deb.NewPackageRefListFromPackageList(dstList))
+		dstRepo.UpdateRefList(deb.NewSplitRefListFromPackageList(dstList))
 
-		err = collectionFactory.LocalRepoCollection().Update(dstRepo)
+		err = collectionFactory.LocalRepoCollection().Update(dstRepo, collectionFactory.RefListCollection())
 		if err != nil {
 			return fmt.Errorf("unable to save: %s", err)
 		}
 
 		if command == "move" { // nolint: goconst
-			srcRepo.UpdateRefList(deb.NewPackageRefListFromPackageList(srcList))
+			srcRepo.UpdateRefList(deb.NewSplitRefListFromPackageList(srcList))
 
-			err = collectionFactory.LocalRepoCollection().Update(srcRepo)
+			err = collectionFactory.LocalRepoCollection().Update(srcRepo, collectionFactory.RefListCollection())
 			if err != nil {
 				return fmt.Errorf("unable to save: %s", err)
 			}
diff --git a/cmd/repo_remove.go b/cmd/repo_remove.go
index 93e8535c7..d3a1159ee 100644
--- a/cmd/repo_remove.go
+++ b/cmd/repo_remove.go
@@ -24,7 +24,7 @@ func aptlyRepoRemove(cmd *commander.Command, args []string) error {
 		return fmt.Errorf("unable to remove: %s", err)
 	}
 
-	err = collectionFactory.LocalRepoCollection().LoadComplete(repo)
+	err = collectionFactory.LocalRepoCollection().LoadComplete(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to remove: %s", err)
 	}
@@ -59,9 +59,9 @@ func aptlyRepoRemove(cmd *commander.Command, args []string) error {
 	if context.Flags().Lookup("dry-run").Value.Get().(bool) {
 		context.Progress().Printf("\nChanges not saved, as dry run has been requested.\n")
 	} else {
-		repo.UpdateRefList(deb.NewPackageRefListFromPackageList(list))
+		repo.UpdateRefList(deb.NewSplitRefListFromPackageList(list))
 
-		err = collectionFactory.LocalRepoCollection().Update(repo)
+		err = collectionFactory.LocalRepoCollection().Update(repo, collectionFactory.RefListCollection())
 		if err != nil {
 			return fmt.Errorf("unable to save: %s", err)
 		}
diff --git a/cmd/repo_rename.go b/cmd/repo_rename.go
index 9234b7c72..459afcbbb 100644
--- a/cmd/repo_rename.go
+++ b/cmd/repo_rename.go
@@ -32,7 +32,7 @@ func aptlyRepoRename(cmd *commander.Command, args []string) error {
 	}
 
 	repo.Name = newName
-	err = collectionFactory.LocalRepoCollection().Update(repo)
+	err = collectionFactory.LocalRepoCollection().Update(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to rename: %s", err)
 	}
diff --git a/cmd/repo_show.go b/cmd/repo_show.go
index a61a5f1f9..741915d12 100644
--- a/cmd/repo_show.go
+++ b/cmd/repo_show.go
@@ -36,7 +36,7 @@ func aptlyRepoShowTxt(_ *commander.Command, args []string) error {
 		return fmt.Errorf("unable to show: %s", err)
 	}
 
-	err = collectionFactory.LocalRepoCollection().LoadComplete(repo)
+	err = collectionFactory.LocalRepoCollection().LoadComplete(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to show: %s", err)
 	}
@@ -63,12 +63,13 @@ func aptlyRepoShowJSON(_ *commander.Command, args []string) error {
 
 	name := args[0]
 
-	repo, err := context.NewCollectionFactory().LocalRepoCollection().ByName(name)
+	collectionFactory := context.NewCollectionFactory()
+	repo, err := collectionFactory.LocalRepoCollection().ByName(name)
 	if err != nil {
 		return fmt.Errorf("unable to show: %s", err)
 	}
 
-	err = context.NewCollectionFactory().LocalRepoCollection().LoadComplete(repo)
+	err = collectionFactory.LocalRepoCollection().LoadComplete(repo, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to show: %s", err)
 	}
@@ -79,7 +80,7 @@ func aptlyRepoShowJSON(_ *commander.Command, args []string) error {
 	if withPackages {
 		if repo.RefList() != nil {
 			var list *deb.PackageList
-			list, err = deb.NewPackageListFromRefList(repo.RefList(), context.NewCollectionFactory().PackageCollection(), context.Progress())
+			list, err = deb.NewPackageListFromRefList(repo.RefList(), collectionFactory.PackageCollection(), context.Progress())
 			if err == nil {
 				packageList = list.FullNames()
 			}
diff --git a/cmd/snapshot_create.go b/cmd/snapshot_create.go
index 000a78d9b..6bc319de3 100644
--- a/cmd/snapshot_create.go
+++ b/cmd/snapshot_create.go
@@ -30,7 +30,7 @@ func aptlySnapshotCreate(cmd *commander.Command, args []string) error {
 			return fmt.Errorf("unable to create snapshot: %s", err)
 		}
 
-		err = collectionFactory.RemoteRepoCollection().LoadComplete(repo)
+		err = collectionFactory.RemoteRepoCollection().LoadComplete(repo, collectionFactory.RefListCollection())
 		if err != nil {
 			return fmt.Errorf("unable to create snapshot: %s", err)
 		}
@@ -50,7 +50,7 @@ func aptlySnapshotCreate(cmd *commander.Command, args []string) error {
 			return fmt.Errorf("unable to create snapshot: %s", err)
 		}
 
-		err = collectionFactory.LocalRepoCollection().LoadComplete(repo)
+		err = collectionFactory.LocalRepoCollection().LoadComplete(repo, collectionFactory.RefListCollection())
 		if err != nil {
 			return fmt.Errorf("unable to create snapshot: %s", err)
 		}
@@ -71,7 +71,7 @@ func aptlySnapshotCreate(cmd *commander.Command, args []string) error {
 		return commander.ErrCommandError
 	}
 
-	err = collectionFactory.SnapshotCollection().Add(snapshot)
+	err = collectionFactory.SnapshotCollection().Add(snapshot, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to add snapshot: %s", err)
 	}
diff --git a/cmd/snapshot_diff.go b/cmd/snapshot_diff.go
index ccbea32ee..19da7fcc9 100644
--- a/cmd/snapshot_diff.go
+++ b/cmd/snapshot_diff.go
@@ -23,7 +23,7 @@ func aptlySnapshotDiff(cmd *commander.Command, args []string) error {
 		return fmt.Errorf("unable to load snapshot A: %s", err)
 	}
 
-	err = collectionFactory.SnapshotCollection().LoadComplete(snapshotA)
+	err = collectionFactory.SnapshotCollection().LoadComplete(snapshotA, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to load snapshot A: %s", err)
 	}
@@ -34,13 +34,13 @@ func aptlySnapshotDiff(cmd *commander.Command, args []string) error {
 		return fmt.Errorf("unable to load snapshot B: %s", err)
 	}
 
-	err = collectionFactory.SnapshotCollection().LoadComplete(snapshotB)
+	err = collectionFactory.SnapshotCollection().LoadComplete(snapshotB, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to load snapshot B: %s", err)
 	}
 
 	// Calculate diff
-	diff, err := snapshotA.RefList().Diff(snapshotB.RefList(), collectionFactory.PackageCollection())
+	diff, err := snapshotA.RefList().Diff(snapshotB.RefList(), collectionFactory.PackageCollection(), nil)
 	if err != nil {
 		return fmt.Errorf("unable to calculate diff: %s", err)
 	}
diff --git a/cmd/snapshot_filter.go b/cmd/snapshot_filter.go
index b81a9cfc2..5aed03b95 100644
--- a/cmd/snapshot_filter.go
+++ b/cmd/snapshot_filter.go
@@ -27,7 +27,7 @@ func aptlySnapshotFilter(cmd *commander.Command, args []string) error {
 		return fmt.Errorf("unable to filter: %s", err)
 	}
 
-	err = collectionFactory.SnapshotCollection().LoadComplete(source)
+	err = collectionFactory.SnapshotCollection().LoadComplete(source, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to filter: %s", err)
 	}
@@ -76,7 +76,7 @@ func aptlySnapshotFilter(cmd *commander.Command, args []string) error {
 	destination := deb.NewSnapshotFromPackageList(args[1], []*deb.Snapshot{source}, result,
 		fmt.Sprintf("Filtered '%s', query was: '%s'", source.Name, strings.Join(args[2:], " ")))
 
-	err = collectionFactory.SnapshotCollection().Add(destination)
+	err = collectionFactory.SnapshotCollection().Add(destination, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to create snapshot: %s", err)
 	}
diff --git a/cmd/snapshot_merge.go b/cmd/snapshot_merge.go
index 0a319a5ab..e9eb0c779 100644
--- a/cmd/snapshot_merge.go
+++ b/cmd/snapshot_merge.go
@@ -24,7 +24,7 @@ func aptlySnapshotMerge(cmd *commander.Command, args []string) error {
 			return fmt.Errorf("unable to load snapshot: %s", err)
 		}
 
-		err = collectionFactory.SnapshotCollection().LoadComplete(sources[i])
+		err = collectionFactory.SnapshotCollection().LoadComplete(sources[i], collectionFactory.RefListCollection())
 		if err != nil {
 			return fmt.Errorf("unable to load snapshot: %s", err)
 		}
@@ -57,7 +57,7 @@ func aptlySnapshotMerge(cmd *commander.Command, args []string) error {
 	destination := deb.NewSnapshotFromRefList(args[0], sources, result,
 		fmt.Sprintf("Merged from sources: %s", strings.Join(sourceDescription, ", ")))
 
-	err = collectionFactory.SnapshotCollection().Add(destination)
+	err = collectionFactory.SnapshotCollection().Add(destination, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to create snapshot: %s", err)
 	}
diff --git a/cmd/snapshot_pull.go b/cmd/snapshot_pull.go
index 884b50ffb..50e8488b8 100644
--- a/cmd/snapshot_pull.go
+++ b/cmd/snapshot_pull.go
@@ -29,7 +29,7 @@ func aptlySnapshotPull(cmd *commander.Command, args []string) error {
 		return fmt.Errorf("unable to pull: %s", err)
 	}
 
-	err = collectionFactory.SnapshotCollection().LoadComplete(snapshot)
+	err = collectionFactory.SnapshotCollection().LoadComplete(snapshot, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to pull: %s", err)
 	}
@@ -40,7 +40,7 @@ func aptlySnapshotPull(cmd *commander.Command, args []string) error {
 		return fmt.Errorf("unable to pull: %s", err)
 	}
 
-	err = collectionFactory.SnapshotCollection().LoadComplete(source)
+	err = collectionFactory.SnapshotCollection().LoadComplete(source, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to pull: %s", err)
 	}
@@ -138,7 +138,7 @@ func aptlySnapshotPull(cmd *commander.Command, args []string) error {
 		destination := deb.NewSnapshotFromPackageList(args[2], []*deb.Snapshot{snapshot, source}, packageList,
 			fmt.Sprintf("Pulled into '%s' with '%s' as source, pull request was: '%s'", snapshot.Name, source.Name, strings.Join(args[3:], " ")))
 
-		err = collectionFactory.SnapshotCollection().Add(destination)
+		err = collectionFactory.SnapshotCollection().Add(destination, collectionFactory.RefListCollection())
 		if err != nil {
 			return fmt.Errorf("unable to create snapshot: %s", err)
 		}
diff --git a/cmd/snapshot_rename.go b/cmd/snapshot_rename.go
index b8ac74cf3..b13b7dca6 100644
--- a/cmd/snapshot_rename.go
+++ b/cmd/snapshot_rename.go
@@ -32,7 +32,7 @@ func aptlySnapshotRename(cmd *commander.Command, args []string) error {
 	}
 
 	snapshot.Name = newName
-	err = collectionFactory.SnapshotCollection().Update(snapshot)
+	err = collectionFactory.SnapshotCollection().Update(snapshot, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to rename: %s", err)
 	}
diff --git a/cmd/snapshot_search.go b/cmd/snapshot_search.go
index d771af7ce..c0244f11c 100644
--- a/cmd/snapshot_search.go
+++ b/cmd/snapshot_search.go
@@ -25,7 +25,7 @@ func aptlySnapshotMirrorRepoSearch(cmd *commander.Command, args []string) error
 	command := cmd.Parent.Name()
 	collectionFactory := context.NewCollectionFactory()
 
-	var reflist *deb.PackageRefList
+	var reflist *deb.SplitRefList
 
 	if command == "snapshot" { // nolint: goconst
 		var snapshot *deb.Snapshot
@@ -34,7 +34,7 @@ func aptlySnapshotMirrorRepoSearch(cmd *commander.Command, args []string) error
 			return fmt.Errorf("unable to search: %s", err)
 		}
 
-		err = collectionFactory.SnapshotCollection().LoadComplete(snapshot)
+		err = collectionFactory.SnapshotCollection().LoadComplete(snapshot, collectionFactory.RefListCollection())
 		if err != nil {
 			return fmt.Errorf("unable to search: %s", err)
 		}
@@ -47,7 +47,7 @@ func aptlySnapshotMirrorRepoSearch(cmd *commander.Command, args []string) error
 			return fmt.Errorf("unable to search: %s", err)
 		}
 
-		err = collectionFactory.RemoteRepoCollection().LoadComplete(repo)
+		err = collectionFactory.RemoteRepoCollection().LoadComplete(repo, collectionFactory.RefListCollection())
 		if err != nil {
 			return fmt.Errorf("unable to search: %s", err)
 		}
@@ -60,7 +60,7 @@ func aptlySnapshotMirrorRepoSearch(cmd *commander.Command, args []string) error
 			return fmt.Errorf("unable to search: %s", err)
 		}
 
-		err = collectionFactory.LocalRepoCollection().LoadComplete(repo)
+		err = collectionFactory.LocalRepoCollection().LoadComplete(repo, collectionFactory.RefListCollection())
 		if err != nil {
 			return fmt.Errorf("unable to search: %s", err)
 		}
diff --git a/cmd/snapshot_show.go b/cmd/snapshot_show.go
index e03a49e58..582b6a9e3 100644
--- a/cmd/snapshot_show.go
+++ b/cmd/snapshot_show.go
@@ -35,7 +35,7 @@ func aptlySnapshotShowTxt(_ *commander.Command, args []string) error {
 		return fmt.Errorf("unable to show: %s", err)
 	}
 
-	err = collectionFactory.SnapshotCollection().LoadComplete(snapshot)
+	err = collectionFactory.SnapshotCollection().LoadComplete(snapshot, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to show: %s", err)
 	}
@@ -86,16 +86,17 @@ func aptlySnapshotShowTxt(_ *commander.Command, args []string) error {
 }
 
 func aptlySnapshotShowJSON(_ *commander.Command, args []string) error {
+	collectionFactory := context.NewCollectionFactory()
 	var err error
 
 	name := args[0]
 
-	snapshot, err := context.NewCollectionFactory().SnapshotCollection().ByName(name)
+	snapshot, err := collectionFactory.SnapshotCollection().ByName(name)
 	if err != nil {
 		return fmt.Errorf("unable to show: %s", err)
 	}
 
-	err = context.NewCollectionFactory().SnapshotCollection().LoadComplete(snapshot)
+	err = collectionFactory.SnapshotCollection().LoadComplete(snapshot, collectionFactory.RefListCollection())
 	if err != nil {
 		return fmt.Errorf("unable to show: %s", err)
 	}
@@ -105,14 +106,14 @@ func aptlySnapshotShowJSON(_ *commander.Command, args []string) error {
 		for _, sourceID := range snapshot.SourceIDs {
 			if snapshot.SourceKind == deb.SourceSnapshot {
 				var source *deb.Snapshot
-				source, err = context.NewCollectionFactory().SnapshotCollection().ByUUID(sourceID)
+				source, err = collectionFactory.SnapshotCollection().ByUUID(sourceID)
 				if err != nil {
 					continue
 				}
 				snapshot.Snapshots = append(snapshot.Snapshots, source)
 			} else if snapshot.SourceKind == deb.SourceLocalRepo {
 				var source *deb.LocalRepo
-				source, err = context.NewCollectionFactory().LocalRepoCollection().ByUUID(sourceID)
+				source, err = collectionFactory.LocalRepoCollection().ByUUID(sourceID)
 				if err != nil {
 					continue
 				}
@@ -133,7 +134,7 @@ func aptlySnapshotShowJSON(_ *commander.Command, args []string) error {
 	if withPackages {
 		if snapshot.RefList() != nil {
 			var list *deb.PackageList
-			list, err = deb.NewPackageListFromRefList(snapshot.RefList(), context.NewCollectionFactory().PackageCollection(), context.Progress())
+			list, err = deb.NewPackageListFromRefList(snapshot.RefList(), collectionFactory.PackageCollection(), context.Progress())
 			if err != nil {
 				return fmt.Errorf("unable to get package list: %s", err)
 			}
diff --git a/cmd/snapshot_verify.go b/cmd/snapshot_verify.go
index f815f29ce..fc566aae3 100644
--- a/cmd/snapshot_verify.go
+++ b/cmd/snapshot_verify.go
@@ -23,7 +23,7 @@ func aptlySnapshotVerify(cmd *commander.Command, args []string) error {
 			return fmt.Errorf("unable to verify: %s", err)
 		}
 
-		err = collectionFactory.SnapshotCollection().LoadComplete(snapshots[i])
+		err = collectionFactory.SnapshotCollection().LoadComplete(snapshots[i], collectionFactory.RefListCollection())
 		if err != nil {
 			return fmt.Errorf("unable to verify: %s", err)
 		}
diff --git a/database/database.go b/database/database.go
index 709a1aa80..03d896b20 100644
--- a/database/database.go
+++ b/database/database.go
@@ -48,6 +48,8 @@ type Storage interface {
 
 	CreateTemporary() (Storage, error)
 
+	GetRecommendedMaxKVSize() int
+
 	Open() error
 	Close() error
 	CompactDB() error
diff --git a/database/goleveldb/database.go b/database/goleveldb/database.go
index a2874a6e6..011681a6b 100644
--- a/database/goleveldb/database.go
+++ b/database/goleveldb/database.go
@@ -9,10 +9,13 @@ import (
 	"github.com/aptly-dev/aptly/database"
 )
 
+const blockSize = 4 * 1024
+
 func internalOpen(path string, throttleCompaction bool) (*leveldb.DB, error) {
 	o := &opt.Options{
 		Filter:                 filter.NewBloomFilter(10),
 		OpenFilesCacheCapacity: 256,
+		BlockSize:              blockSize,
 	}
 
 	if throttleCompaction {
diff --git a/database/goleveldb/storage.go b/database/goleveldb/storage.go
index 37acf3d83..1281f3fbc 100644
--- a/database/goleveldb/storage.go
+++ b/database/goleveldb/storage.go
@@ -16,6 +16,17 @@ type storage struct {
 	db   *leveldb.DB
 }
 
+func (s *storage) GetRecommendedMaxKVSize() int {
+	// The block size configured is not actually a *set* block size, but rather a
+	// *minimum*. LevelDB only checks if a block is full after a new key/value pair is
+	// written, meaning that blocks will tend to overflow a bit.
+	// Therefore, using the default block size as the max value size will ensure
+	// that a new block will only contain a single value and that the size will
+	// only ever be as large as around double the block size (if the block was
+	// nearly full before the new items were added).
+	return blockSize
+}
+
 // CreateTemporary creates new DB of the same type in temp dir
 func (s *storage) CreateTemporary() (database.Storage, error) {
 	tempdir, err := os.MkdirTemp("", "aptly")
diff --git a/deb/changes.go b/deb/changes.go
index c264986ab..6c8bf8812 100644
--- a/deb/changes.go
+++ b/deb/changes.go
@@ -291,7 +291,8 @@ func CollectChangesFiles(locations []string, reporter aptly.ResultReporter) (cha
 // ImportChangesFiles imports referenced files in changes files into local repository
 func ImportChangesFiles(changesFiles []string, reporter aptly.ResultReporter, acceptUnsigned, ignoreSignatures, forceReplace, noRemoveFiles bool,
 	verifier pgp.Verifier, repoTemplate *template.Template, progress aptly.Progress, localRepoCollection *LocalRepoCollection, packageCollection *PackageCollection,
-	pool aptly.PackagePool, checksumStorageProvider aptly.ChecksumStorageProvider, uploaders *Uploaders, parseQuery parseQuery) (processedFiles []string, failedFiles []string, err error) {
+	reflistCollection *RefListCollection, pool aptly.PackagePool, checksumStorageProvider aptly.ChecksumStorageProvider, uploaders *Uploaders,
+	parseQuery parseQuery) (processedFiles []string, failedFiles []string, err error) {
 
 	for _, path := range changesFiles {
 		var changes *Changes
@@ -359,7 +360,7 @@ func ImportChangesFiles(changesFiles []string, reporter aptly.ResultReporter, ac
 			}
 		}
 
-		err = localRepoCollection.LoadComplete(repo)
+		err = localRepoCollection.LoadComplete(repo, reflistCollection)
 		if err != nil {
 			return nil, nil, fmt.Errorf("unable to load repo: %s", err)
 		}
@@ -382,9 +383,9 @@ func ImportChangesFiles(changesFiles []string, reporter aptly.ResultReporter, ac
 			return nil, nil, fmt.Errorf("unable to import package files: %s", err)
 		}
 
-		repo.UpdateRefList(NewPackageRefListFromPackageList(list))
+		repo.UpdateRefList(NewSplitRefListFromPackageList(list))
 
-		err = localRepoCollection.Update(repo)
+		err = localRepoCollection.Update(repo, reflistCollection)
 		if err != nil {
 			return nil, nil, fmt.Errorf("unable to save: %s", err)
 		}
diff --git a/deb/changes_test.go b/deb/changes_test.go
index b7dc4d95d..1d50d610a 100644
--- a/deb/changes_test.go
+++ b/deb/changes_test.go
@@ -21,6 +21,7 @@ type ChangesSuite struct {
 	db                  database.Storage
 	localRepoCollection *LocalRepoCollection
 	packageCollection   *PackageCollection
+	reflistCollection   *RefListCollection
 	packagePool         aptly.PackagePool
 	checksumStorage     aptly.ChecksumStorage
 	progress            aptly.Progress
@@ -42,6 +43,7 @@ func (s *ChangesSuite) SetUpTest(c *C) {
 	s.db, _ = goleveldb.NewOpenDB(c.MkDir())
 	s.localRepoCollection = NewLocalRepoCollection(s.db)
 	s.packageCollection = NewPackageCollection(s.db)
+	s.reflistCollection = NewRefListCollection(s.db)
 
 	s.checksumStorage = files.NewMockChecksumStorage()
 	s.packagePool = files.NewPackagePool(s.Dir, false)
@@ -88,7 +90,7 @@ func (s *ChangesSuite) TestCollectChangesFiles(c *C) {
 
 func (s *ChangesSuite) TestImportChangesFiles(c *C) {
 	repo := NewLocalRepo("test", "Test Comment")
-	c.Assert(s.localRepoCollection.Add(repo), IsNil)
+	c.Assert(s.localRepoCollection.Add(repo, s.reflistCollection), IsNil)
 
 	origFailedFiles := []string{
 		"testdata/changes/calamares.changes",
@@ -124,7 +126,8 @@ func (s *ChangesSuite) TestImportChangesFiles(c *C) {
 	processedFiles, failedFiles, err := ImportChangesFiles(
 		append(changesFiles, "testdata/changes/notexistent.changes"),
 		s.Reporter, true, true, false, false, &NullVerifier{},
-		template.Must(template.New("test").Parse("test")), s.progress, s.localRepoCollection, s.packageCollection, s.packagePool, func(database.ReaderWriter) aptly.ChecksumStorage { return s.checksumStorage },
+		template.Must(template.New("test").Parse("test")), s.progress, s.localRepoCollection, s.packageCollection, s.reflistCollection, s.packagePool,
+		func(database.ReaderWriter) aptly.ChecksumStorage { return s.checksumStorage },
 		nil, nil)
 	c.Assert(err, IsNil)
 	c.Check(failedFiles, DeepEquals, append(expectedFailedFiles, "testdata/changes/notexistent.changes"))
@@ -133,7 +136,7 @@ func (s *ChangesSuite) TestImportChangesFiles(c *C) {
 
 func (s *ChangesSuite) TestImportDbgsymWithVersionedSourceField(c *C) {
 	repo := NewLocalRepo("test", "Test Comment")
-	c.Assert(s.localRepoCollection.Add(repo), IsNil)
+	c.Assert(s.localRepoCollection.Add(repo, s.reflistCollection), IsNil)
 
 	changesFiles, failedFiles := CollectChangesFiles(
 		[]string{"testdata/dbgsym-with-source-version"}, s.Reporter)
@@ -142,7 +145,8 @@ func (s *ChangesSuite) TestImportDbgsymWithVersionedSourceField(c *C) {
 
 	_, failedFiles, err := ImportChangesFiles(
 		changesFiles, s.Reporter, true, true, false, true, &NullVerifier{},
-		template.Must(template.New("test").Parse("test")), s.progress, s.localRepoCollection, s.packageCollection, s.packagePool, func(database.ReaderWriter) aptly.ChecksumStorage { return s.checksumStorage },
+		template.Must(template.New("test").Parse("test")), s.progress, s.localRepoCollection, s.packageCollection, s.reflistCollection, s.packagePool,
+		func(database.ReaderWriter) aptly.ChecksumStorage { return s.checksumStorage },
 		nil, nil)
 	c.Assert(err, IsNil)
 	c.Check(failedFiles, IsNil)
diff --git a/deb/collections.go b/deb/collections.go
index 7dfe85235..ff711e265 100644
--- a/deb/collections.go
+++ b/deb/collections.go
@@ -16,6 +16,7 @@ type CollectionFactory struct {
 	snapshots      *SnapshotCollection
 	localRepos     *LocalRepoCollection
 	publishedRepos *PublishedRepoCollection
+	reflists       *RefListCollection
 	checksums      *ChecksumCollection
 }
 
@@ -91,6 +92,17 @@ func (factory *CollectionFactory) PublishedRepoCollection() *PublishedRepoCollec
 	return factory.publishedRepos
 }
 
+func (factory *CollectionFactory) RefListCollection() *RefListCollection {
+	factory.Lock()
+	defer factory.Unlock()
+
+	if factory.reflists == nil {
+		factory.reflists = NewRefListCollection(factory.db)
+	}
+
+	return factory.reflists
+}
+
 // ChecksumCollection returns (or creates) new ChecksumCollection
 func (factory *CollectionFactory) ChecksumCollection(db database.ReaderWriter) aptly.ChecksumStorage {
 	factory.Lock()
diff --git a/deb/graph.go b/deb/graph.go
index 16a7ce854..77421c3a5 100644
--- a/deb/graph.go
+++ b/deb/graph.go
@@ -33,7 +33,7 @@ func BuildGraph(collectionFactory *CollectionFactory, layout string) (gographviz
 	existingNodes := map[string]bool{}
 
 	err = collectionFactory.RemoteRepoCollection().ForEach(func(repo *RemoteRepo) error {
-		e := collectionFactory.RemoteRepoCollection().LoadComplete(repo)
+		e := collectionFactory.RemoteRepoCollection().LoadComplete(repo, collectionFactory.RefListCollection())
 		if e != nil {
 			return e
 		}
@@ -55,7 +55,7 @@ func BuildGraph(collectionFactory *CollectionFactory, layout string) (gographviz
 	}
 
 	err = collectionFactory.LocalRepoCollection().ForEach(func(repo *LocalRepo) error {
-		e := collectionFactory.LocalRepoCollection().LoadComplete(repo)
+		e := collectionFactory.LocalRepoCollection().LoadComplete(repo, collectionFactory.RefListCollection())
 		if e != nil {
 			return e
 		}
@@ -81,7 +81,7 @@ func BuildGraph(collectionFactory *CollectionFactory, layout string) (gographviz
 	})
 
 	err = collectionFactory.SnapshotCollection().ForEach(func(snapshot *Snapshot) error {
-		e := collectionFactory.SnapshotCollection().LoadComplete(snapshot)
+		e := collectionFactory.SnapshotCollection().LoadComplete(snapshot, collectionFactory.RefListCollection())
 		if e != nil {
 			return e
 		}
diff --git a/deb/list.go b/deb/list.go
index ec14bb982..e59390f6b 100644
--- a/deb/list.go
+++ b/deb/list.go
@@ -90,7 +90,7 @@ func NewPackageListWithDuplicates(duplicates bool, capacity int) *PackageList {
 }
 
 // NewPackageListFromRefList loads packages list from PackageRefList
-func NewPackageListFromRefList(reflist *PackageRefList, collection *PackageCollection, progress aptly.Progress) (*PackageList, error) {
+func NewPackageListFromRefList(reflist AnyRefList, collection *PackageCollection, progress aptly.Progress) (*PackageList, error) {
 	// empty reflist
 	if reflist == nil {
 		return NewPackageList(), nil
diff --git a/deb/local.go b/deb/local.go
index 1b09fdbda..4bb3843a6 100644
--- a/deb/local.go
+++ b/deb/local.go
@@ -26,7 +26,7 @@ type LocalRepo struct {
 	// Uploaders configuration
 	Uploaders *Uploaders `codec:"Uploaders,omitempty" json:"-"`
 	// "Snapshot" of current list of packages
-	packageRefs *PackageRefList
+	packageRefs *SplitRefList
 }
 
 // NewLocalRepo creates new instance of Debian local repository
@@ -55,13 +55,13 @@ func (repo *LocalRepo) NumPackages() int {
 }
 
 // RefList returns package list for repo
-func (repo *LocalRepo) RefList() *PackageRefList {
+func (repo *LocalRepo) RefList() *SplitRefList {
 	return repo.packageRefs
 }
 
 // UpdateRefList changes package list for local repo
-func (repo *LocalRepo) UpdateRefList(reflist *PackageRefList) {
-	repo.packageRefs = reflist
+func (repo *LocalRepo) UpdateRefList(sl *SplitRefList) {
+	repo.packageRefs = sl
 }
 
 // Encode does msgpack encoding of LocalRepo
@@ -140,14 +140,14 @@ func (collection *LocalRepoCollection) search(filter func(*LocalRepo) bool, uniq
 }
 
 // Add appends new repo to collection and saves it
-func (collection *LocalRepoCollection) Add(repo *LocalRepo) error {
+func (collection *LocalRepoCollection) Add(repo *LocalRepo, reflistCollection *RefListCollection) error {
 	_, err := collection.ByName(repo.Name)
 
 	if err == nil {
 		return fmt.Errorf("local repo with name %s already exists", repo.Name)
 	}
 
-	err = collection.Update(repo)
+	err = collection.Update(repo, reflistCollection)
 	if err != nil {
 		return err
 	}
@@ -157,27 +157,25 @@ func (collection *LocalRepoCollection) Add(repo *LocalRepo) error {
 }
 
 // Update stores updated information about repo in DB
-func (collection *LocalRepoCollection) Update(repo *LocalRepo) error {
+func (collection *LocalRepoCollection) Update(repo *LocalRepo, reflistCollection *RefListCollection) error {
 	batch := collection.db.CreateBatch()
 	batch.Put(repo.Key(), repo.Encode())
 	if repo.packageRefs != nil {
-		batch.Put(repo.RefKey(), repo.packageRefs.Encode())
+		bc := reflistCollection.NewBatch(batch)
+		reflistCollection.UpdateInBatch(repo.packageRefs, repo.RefKey(), bc)
 	}
 	return batch.Write()
 }
 
 // LoadComplete loads additional information for local repo
-func (collection *LocalRepoCollection) LoadComplete(repo *LocalRepo) error {
-	encoded, err := collection.db.Get(repo.RefKey())
+func (collection *LocalRepoCollection) LoadComplete(repo *LocalRepo, reflistCollection *RefListCollection) error {
+	repo.packageRefs = NewSplitRefList()
+	err := reflistCollection.LoadComplete(repo.packageRefs, repo.RefKey())
 	if err == database.ErrNotFound {
 		return nil
 	}
-	if err != nil {
-		return err
-	}
 
-	repo.packageRefs = &PackageRefList{}
-	return repo.packageRefs.Decode(encoded)
+	return err
 }
 
 // ByName looks up repository by name
diff --git a/deb/local_test.go b/deb/local_test.go
index c9072b7dc..b87b1b624 100644
--- a/deb/local_test.go
+++ b/deb/local_test.go
@@ -12,7 +12,7 @@ import (
 type LocalRepoSuite struct {
 	db      database.Storage
 	list    *PackageList
-	reflist *PackageRefList
+	reflist *SplitRefList
 	repo    *LocalRepo
 }
 
@@ -24,7 +24,7 @@ func (s *LocalRepoSuite) SetUpTest(c *C) {
 	s.list.Add(&Package{Name: "lib", Version: "1.7", Architecture: "i386"})
 	s.list.Add(&Package{Name: "app", Version: "1.9", Architecture: "amd64"})
 
-	s.reflist = NewPackageRefListFromPackageList(s.list)
+	s.reflist = NewSplitRefListFromPackageList(s.list)
 
 	s.repo = NewLocalRepo("lrepo", "Super repo")
 	s.repo.packageRefs = s.reflist
@@ -75,10 +75,11 @@ func (s *LocalRepoSuite) TestRefKey(c *C) {
 }
 
 type LocalRepoCollectionSuite struct {
-	db         database.Storage
-	collection *LocalRepoCollection
-	list       *PackageList
-	reflist    *PackageRefList
+	db                database.Storage
+	collection        *LocalRepoCollection
+	reflistCollection *RefListCollection
+	list              *PackageList
+	reflist           *SplitRefList
 }
 
 var _ = Suite(&LocalRepoCollectionSuite{})
@@ -86,12 +87,13 @@ var _ = Suite(&LocalRepoCollectionSuite{})
 func (s *LocalRepoCollectionSuite) SetUpTest(c *C) {
 	s.db, _ = goleveldb.NewOpenDB(c.MkDir())
 	s.collection = NewLocalRepoCollection(s.db)
+	s.reflistCollection = NewRefListCollection(s.db)
 
 	s.list = NewPackageList()
 	s.list.Add(&Package{Name: "lib", Version: "1.7", Architecture: "i386"})
 	s.list.Add(&Package{Name: "app", Version: "1.9", Architecture: "amd64"})
 
-	s.reflist = NewPackageRefListFromPackageList(s.list)
+	s.reflist = NewSplitRefListFromRefList(NewPackageRefListFromPackageList(s.list))
 }
 
 func (s *LocalRepoCollectionSuite) TearDownTest(c *C) {
@@ -103,8 +105,8 @@ func (s *LocalRepoCollectionSuite) TestAddByName(c *C) {
 	c.Assert(err, ErrorMatches, "*.not found")
 
 	repo := NewLocalRepo("local1", "Comment 1")
-	c.Assert(s.collection.Add(repo), IsNil)
-	c.Assert(s.collection.Add(repo), ErrorMatches, ".*already exists")
+	c.Assert(s.collection.Add(repo, s.reflistCollection), IsNil)
+	c.Assert(s.collection.Add(repo, s.reflistCollection), ErrorMatches, ".*already exists")
 
 	r, err := s.collection.ByName("local1")
 	c.Assert(err, IsNil)
@@ -121,7 +123,7 @@ func (s *LocalRepoCollectionSuite) TestByUUID(c *C) {
 	c.Assert(err, ErrorMatches, "*.not found")
 
 	repo := NewLocalRepo("local1", "Comment 1")
-	c.Assert(s.collection.Add(repo), IsNil)
+	c.Assert(s.collection.Add(repo, s.reflistCollection), IsNil)
 
 	r, err := s.collection.ByUUID(repo.UUID)
 	c.Assert(err, IsNil)
@@ -135,7 +137,7 @@ func (s *LocalRepoCollectionSuite) TestByUUID(c *C) {
 
 func (s *LocalRepoCollectionSuite) TestUpdateLoadComplete(c *C) {
 	repo := NewLocalRepo("local1", "Comment 1")
-	c.Assert(s.collection.Update(repo), IsNil)
+	c.Assert(s.collection.Update(repo, s.reflistCollection), IsNil)
 
 	collection := NewLocalRepoCollection(s.db)
 	r, err := collection.ByName("local1")
@@ -143,20 +145,20 @@ func (s *LocalRepoCollectionSuite) TestUpdateLoadComplete(c *C) {
 	c.Assert(r.packageRefs, IsNil)
 
 	repo.packageRefs = s.reflist
-	c.Assert(s.collection.Update(repo), IsNil)
+	c.Assert(s.collection.Update(repo, s.reflistCollection), IsNil)
 
 	collection = NewLocalRepoCollection(s.db)
 	r, err = collection.ByName("local1")
 	c.Assert(err, IsNil)
 	c.Assert(r.packageRefs, IsNil)
 	c.Assert(r.NumPackages(), Equals, 0)
-	c.Assert(s.collection.LoadComplete(r), IsNil)
+	c.Assert(s.collection.LoadComplete(r, s.reflistCollection), IsNil)
 	c.Assert(r.NumPackages(), Equals, 2)
 }
 
 func (s *LocalRepoCollectionSuite) TestForEachAndLen(c *C) {
 	repo := NewLocalRepo("local1", "Comment 1")
-	s.collection.Add(repo)
+	s.collection.Add(repo, s.reflistCollection)
 
 	count := 0
 	err := s.collection.ForEach(func(*LocalRepo) error {
@@ -178,10 +180,10 @@ func (s *LocalRepoCollectionSuite) TestForEachAndLen(c *C) {
 
 func (s *LocalRepoCollectionSuite) TestDrop(c *C) {
 	repo1 := NewLocalRepo("local1", "Comment 1")
-	s.collection.Add(repo1)
+	s.collection.Add(repo1, s.reflistCollection)
 
 	repo2 := NewLocalRepo("local2", "Comment 2")
-	s.collection.Add(repo2)
+	s.collection.Add(repo2, s.reflistCollection)
 
 	r1, _ := s.collection.ByUUID(repo1.UUID)
 	c.Check(r1, Equals, repo1)
diff --git a/deb/publish.go b/deb/publish.go
index 0098bb212..072e1e5e7 100644
--- a/deb/publish.go
+++ b/deb/publish.go
@@ -27,7 +27,7 @@ type repoSourceItem struct {
 	// Pointer to local repo if SourceKind == "local"
 	localRepo *LocalRepo
 	// Package references is SourceKind == "local"
-	packageRefs *PackageRefList
+	packageRefs *SplitRefList
 }
 
 // PublishedRepo is a published for http/ftp representation of snapshot as Debian repository
@@ -394,7 +394,7 @@ func (p *PublishedRepo) RefKey(component string) []byte {
 }
 
 // RefList returns list of package refs in local repo
-func (p *PublishedRepo) RefList(component string) *PackageRefList {
+func (p *PublishedRepo) RefList(component string) *SplitRefList {
 	item := p.sourceItems[component]
 	if p.SourceKind == SourceLocalRepo {
 		return item.packageRefs
@@ -950,14 +950,14 @@ func (collection *PublishedRepoCollection) loadList() {
 }
 
 // Add appends new repo to collection and saves it
-func (collection *PublishedRepoCollection) Add(repo *PublishedRepo) error {
+func (collection *PublishedRepoCollection) Add(repo *PublishedRepo, reflistCollection *RefListCollection) error {
 	collection.loadList()
 
 	if collection.CheckDuplicate(repo) != nil {
 		return fmt.Errorf("published repo with storage/prefix/distribution %s/%s/%s already exists", repo.Storage, repo.Prefix, repo.Distribution)
 	}
 
-	err := collection.Update(repo)
+	err := collection.Update(repo, reflistCollection)
 	if err != nil {
 		return err
 	}
@@ -980,13 +980,14 @@ func (collection *PublishedRepoCollection) CheckDuplicate(repo *PublishedRepo) *
 }
 
 // Update stores updated information about repo in DB
-func (collection *PublishedRepoCollection) Update(repo *PublishedRepo) error {
+func (collection *PublishedRepoCollection) Update(repo *PublishedRepo, reflistCollection *RefListCollection) error {
 	batch := collection.db.CreateBatch()
 	batch.Put(repo.Key(), repo.Encode())
 
 	if repo.SourceKind == SourceLocalRepo {
+		rb := reflistCollection.NewBatch(batch)
 		for component, item := range repo.sourceItems {
-			batch.Put(repo.RefKey(component), item.packageRefs.Encode())
+			reflistCollection.UpdateInBatch(item.packageRefs, repo.RefKey(component), rb)
 		}
 	}
 	return batch.Write()
@@ -1019,7 +1020,7 @@ func (collection *PublishedRepoCollection) LoadShallow(repo *PublishedRepo, coll
 				return
 			}
 
-			item.packageRefs = &PackageRefList{}
+			item.packageRefs = NewSplitRefList()
 			repo.sourceItems[component] = item
 		}
 	} else {
@@ -1035,35 +1036,29 @@ func (collection *PublishedRepoCollection) LoadComplete(repo *PublishedRepo, col
 
 	if repo.SourceKind == SourceSnapshot {
 		for _, item := range repo.sourceItems {
-			err = collectionFactory.SnapshotCollection().LoadComplete(item.snapshot)
+			err = collectionFactory.SnapshotCollection().LoadComplete(item.snapshot, collectionFactory.RefListCollection())
 			if err != nil {
 				return
 			}
 		}
 	} else if repo.SourceKind == SourceLocalRepo {
 		for component, item := range repo.sourceItems {
-			err = collectionFactory.LocalRepoCollection().LoadComplete(item.localRepo)
+			err = collectionFactory.LocalRepoCollection().LoadComplete(item.localRepo, collectionFactory.RefListCollection())
 			if err != nil {
 				return
 			}
 
-			var encoded []byte
-			encoded, err = collection.db.Get(repo.RefKey(component))
+			err = collectionFactory.RefListCollection().LoadComplete(item.packageRefs, repo.RefKey(component))
 			if err != nil {
 				// < 0.6 saving w/o component name
 				if err == database.ErrNotFound && len(repo.Sources) == 1 {
-					encoded, err = collection.db.Get(repo.RefKey(""))
+					err = collectionFactory.RefListCollection().LoadComplete(item.packageRefs, repo.RefKey(""))
 				}
 
 				if err != nil {
 					return
 				}
 			}
-
-			err = item.packageRefs.Decode(encoded)
-			if err != nil {
-				return
-			}
 		}
 	} else {
 		panic("unknown SourceKind")
@@ -1168,6 +1163,11 @@ func (collection *PublishedRepoCollection) listReferencedFilesByComponent(prefix
 	referencedFiles := map[string][]string{}
 	processedComponentRefs := map[string]*PackageRefList{}
 
+	processedComponentBuckets := map[string]*RefListDigestSet{}
+	for _, component := range components {
+		processedComponentBuckets[component] = NewRefListDigestSet()
+	}
+
 	for _, r := range collection.list {
 		if r.Prefix == prefix {
 			matches := false
@@ -1191,36 +1191,51 @@ func (collection *PublishedRepoCollection) listReferencedFilesByComponent(prefix
 
 			for _, component := range components {
 				if utils.StrSliceHasItem(repoComponents, component) {
-					unseenRefs := r.RefList(component)
-					processedRefs := processedComponentRefs[component]
-					if processedRefs != nil {
-						unseenRefs = unseenRefs.Subtract(processedRefs)
-					} else {
-						processedRefs = NewPackageRefList()
-					}
+					processedBuckets := processedComponentBuckets[component]
 
-					if unseenRefs.Len() == 0 {
-						continue
-					}
-					processedComponentRefs[component] = processedRefs.Merge(unseenRefs, false, true)
+					err := r.RefList(component).ForEachBucket(func(digest []byte, bucket *PackageRefList) error {
+						if processedBuckets.Has(digest) {
+							return nil
+						}
+						processedBuckets.Add(digest)
 
-					packageList, err := NewPackageListFromRefList(unseenRefs, collectionFactory.PackageCollection(), progress)
-					if err != nil {
-						return nil, err
-					}
+						unseenRefs := bucket
+						processedRefs := processedComponentRefs[component]
+						if processedRefs != nil {
+							unseenRefs = unseenRefs.Subtract(processedRefs)
+						} else {
+							processedRefs = NewPackageRefList()
+						}
 
-					packageList.ForEach(func(p *Package) error {
-						poolDir, err := p.PoolDirectory()
+						if unseenRefs.Len() == 0 {
+							return nil
+						}
+						processedComponentRefs[component] = processedRefs.Merge(unseenRefs, false, true)
+
+						packageList, err := NewPackageListFromRefList(unseenRefs, collectionFactory.PackageCollection(), progress)
 						if err != nil {
 							return err
 						}
 
-						for _, f := range p.Files() {
-							referencedFiles[component] = append(referencedFiles[component], filepath.Join(poolDir, f.Filename))
-						}
+						packageList.ForEach(func(p *Package) error {
+							poolDir, err := p.PoolDirectory()
+							if err != nil {
+								return err
+							}
+
+							for _, f := range p.Files() {
+								referencedFiles[component] = append(referencedFiles[component], filepath.Join(poolDir, f.Filename))
+							}
+
+							return nil
+						})
 
 						return nil
 					})
+
+					if err != nil {
+						return nil, err
+					}
 				}
 			}
 		}
diff --git a/deb/publish_bench_test.go b/deb/publish_bench_test.go
index b135a8b8c..f1d87e1eb 100644
--- a/deb/publish_bench_test.go
+++ b/deb/publish_bench_test.go
@@ -31,6 +31,7 @@ func BenchmarkListReferencedFiles(b *testing.B) {
 	packageCollection := factory.PackageCollection()
 	repoCollection := factory.LocalRepoCollection()
 	publishCollection := factory.PublishedRepoCollection()
+	reflistCollection := factory.RefListCollection()
 
 	sharedRefs := NewPackageRefList()
 	{
@@ -91,14 +92,14 @@ func BenchmarkListReferencedFiles(b *testing.B) {
 		repo := NewLocalRepo(fmt.Sprintf("repo%d", repoIndex), "comment")
 		repo.DefaultDistribution = fmt.Sprintf("dist%d", repoIndex)
 		repo.DefaultComponent = defaultComponent
-		repo.UpdateRefList(refs.Merge(sharedRefs, false, true))
-		repoCollection.Add(repo)
+		repo.UpdateRefList(NewSplitRefListFromRefList(refs.Merge(sharedRefs, false, true)))
+		repoCollection.Add(repo, reflistCollection)
 
 		publish, err := NewPublishedRepo("", "test", "", nil, []string{defaultComponent}, []interface{}{repo}, factory)
 		if err != nil {
 			b.Fatal(err)
 		}
-		publishCollection.Add(publish)
+		publishCollection.Add(publish, reflistCollection)
 	}
 
 	db.CompactDB()
diff --git a/deb/publish_test.go b/deb/publish_test.go
index 6fdad759a..9fe421cd5 100644
--- a/deb/publish_test.go
+++ b/deb/publish_test.go
@@ -82,6 +82,7 @@ type PublishedRepoSuite struct {
 	db                                  database.Storage
 	factory                             *CollectionFactory
 	packageCollection                   *PackageCollection
+	reflistCollection                   *RefListCollection
 }
 
 var _ = Suite(&PublishedRepoSuite{})
@@ -113,21 +114,22 @@ func (s *PublishedRepoSuite) SetUpTest(c *C) {
 	s.p2.UpdateFiles(s.p1.Files())
 	s.p3.UpdateFiles(s.p1.Files())
 
-	s.reflist = NewPackageRefListFromPackageList(s.list)
+	s.reflist = NewSplitRefListFromPackageList(s.list)
+	s.reflistCollection = s.factory.RefListCollection()
 
 	repo, _ := NewRemoteRepo("yandex", "http://mirror.yandex.ru/debian/", "squeeze", []string{"main"}, []string{}, false, false, false)
 	repo.packageRefs = s.reflist
-	s.factory.RemoteRepoCollection().Add(repo)
+	s.factory.RemoteRepoCollection().Add(repo, s.reflistCollection)
 
 	s.localRepo = NewLocalRepo("local1", "comment1")
 	s.localRepo.packageRefs = s.reflist
-	s.factory.LocalRepoCollection().Add(s.localRepo)
+	s.factory.LocalRepoCollection().Add(s.localRepo, s.reflistCollection)
 
 	s.snapshot, _ = NewSnapshotFromRepository("snap", repo)
-	s.factory.SnapshotCollection().Add(s.snapshot)
+	s.factory.SnapshotCollection().Add(s.snapshot, s.reflistCollection)
 
 	s.snapshot2, _ = NewSnapshotFromRepository("snap", repo)
-	s.factory.SnapshotCollection().Add(s.snapshot2)
+	s.factory.SnapshotCollection().Add(s.snapshot2, s.reflistCollection)
 
 	s.packageCollection = s.factory.PackageCollection()
 	s.packageCollection.Update(s.p1)
@@ -336,7 +338,7 @@ func (s *PublishedRepoSuite) TestDistributionComponentGuessing(c *C) {
 
 	s.localRepo.DefaultDistribution = "precise"
 	s.localRepo.DefaultComponent = "contrib"
-	s.factory.LocalRepoCollection().Update(s.localRepo)
+	s.factory.LocalRepoCollection().Update(s.localRepo, s.reflistCollection)
 
 	repo, err = NewPublishedRepo("", "ppa", "", nil, []string{""}, []interface{}{s.localRepo}, s.factory)
 	c.Check(err, IsNil)
@@ -494,6 +496,7 @@ type PublishedRepoCollectionSuite struct {
 	db                                database.Storage
 	factory                           *CollectionFactory
 	snapshotCollection                *SnapshotCollection
+	reflistCollection                 *RefListCollection
 	collection                        *PublishedRepoCollection
 	snap1, snap2                      *Snapshot
 	localRepo                         *LocalRepo
@@ -509,22 +512,23 @@ func (s *PublishedRepoCollectionSuite) SetUpTest(c *C) {
 	s.factory = NewCollectionFactory(s.db)
 
 	s.snapshotCollection = s.factory.SnapshotCollection()
+	s.reflistCollection = s.factory.RefListCollection()
 
 	snap1Refs := NewPackageRefList()
 	snap1Refs.Refs = [][]byte{s.p1.Key(""), s.p2.Key("")}
 	sort.Sort(snap1Refs)
-	s.snap1 = NewSnapshotFromRefList("snap1", []*Snapshot{}, snap1Refs, "desc1")
+	s.snap1 = NewSnapshotFromRefList("snap1", []*Snapshot{}, NewSplitRefListFromRefList(snap1Refs), "desc1")
 
 	snap2Refs := NewPackageRefList()
 	snap2Refs.Refs = [][]byte{s.p3.Key("")}
 	sort.Sort(snap2Refs)
-	s.snap2 = NewSnapshotFromRefList("snap2", []*Snapshot{}, snap2Refs, "desc2")
+	s.snap2 = NewSnapshotFromRefList("snap2", []*Snapshot{}, NewSplitRefListFromRefList(snap2Refs), "desc2")
 
-	s.snapshotCollection.Add(s.snap1)
-	s.snapshotCollection.Add(s.snap2)
+	s.snapshotCollection.Add(s.snap1, s.reflistCollection)
+	s.snapshotCollection.Add(s.snap2, s.reflistCollection)
 
 	s.localRepo = NewLocalRepo("local1", "comment1")
-	s.factory.LocalRepoCollection().Add(s.localRepo)
+	s.factory.LocalRepoCollection().Add(s.localRepo, s.reflistCollection)
 
 	s.repo1, _ = NewPublishedRepo("", "ppa", "anaconda", []string{}, []string{"main"}, []interface{}{s.snap1}, s.factory)
 	s.repo2, _ = NewPublishedRepo("", "", "anaconda", []string{}, []string{"main", "contrib"}, []interface{}{s.snap2, s.snap1}, s.factory)
@@ -543,14 +547,14 @@ func (s *PublishedRepoCollectionSuite) TestAddByStoragePrefixDistribution(c *C)
 	_, err := s.collection.ByStoragePrefixDistribution("", "ppa", "anaconda")
 	c.Assert(err, ErrorMatches, "*.not found")
 
-	c.Assert(s.collection.Add(s.repo1), IsNil)
-	c.Assert(s.collection.Add(s.repo1), ErrorMatches, ".*already exists")
+	c.Assert(s.collection.Add(s.repo1, s.reflistCollection), IsNil)
+	c.Assert(s.collection.Add(s.repo1, s.reflistCollection), ErrorMatches, ".*already exists")
 	c.Assert(s.collection.CheckDuplicate(s.repo2), IsNil)
-	c.Assert(s.collection.Add(s.repo2), IsNil)
-	c.Assert(s.collection.Add(s.repo3), ErrorMatches, ".*already exists")
+	c.Assert(s.collection.Add(s.repo2, s.reflistCollection), IsNil)
+	c.Assert(s.collection.Add(s.repo3, s.reflistCollection), ErrorMatches, ".*already exists")
 	c.Assert(s.collection.CheckDuplicate(s.repo3), Equals, s.repo1)
-	c.Assert(s.collection.Add(s.repo4), IsNil)
-	c.Assert(s.collection.Add(s.repo5), IsNil)
+	c.Assert(s.collection.Add(s.repo4, s.reflistCollection), IsNil)
+	c.Assert(s.collection.Add(s.repo5, s.reflistCollection), IsNil)
 
 	r, err := s.collection.ByStoragePrefixDistribution("", "ppa", "anaconda")
 	c.Assert(err, IsNil)
@@ -576,7 +580,7 @@ func (s *PublishedRepoCollectionSuite) TestByUUID(c *C) {
 	_, err := s.collection.ByUUID(s.repo1.UUID)
 	c.Assert(err, ErrorMatches, "*.not found")
 
-	c.Assert(s.collection.Add(s.repo1), IsNil)
+	c.Assert(s.collection.Add(s.repo1, s.reflistCollection), IsNil)
 
 	r, err := s.collection.ByUUID(s.repo1.UUID)
 	c.Assert(err, IsNil)
@@ -587,8 +591,8 @@ func (s *PublishedRepoCollectionSuite) TestByUUID(c *C) {
 }
 
 func (s *PublishedRepoCollectionSuite) TestUpdateLoadComplete(c *C) {
-	c.Assert(s.collection.Update(s.repo1), IsNil)
-	c.Assert(s.collection.Update(s.repo4), IsNil)
+	c.Assert(s.collection.Update(s.repo1, s.reflistCollection), IsNil)
+	c.Assert(s.collection.Update(s.repo4, s.reflistCollection), IsNil)
 
 	collection := NewPublishedRepoCollection(s.db)
 	r, err := collection.ByStoragePrefixDistribution("", "ppa", "anaconda")
@@ -636,7 +640,7 @@ func (s *PublishedRepoCollectionSuite) TestLoadPre0_6(c *C) {
 	encoder.Encode(&old)
 
 	c.Assert(s.db.Put(s.repo1.Key(), buf.Bytes()), IsNil)
-	c.Assert(s.db.Put(s.repo1.RefKey(""), s.localRepo.RefList().Encode()), IsNil)
+	c.Assert(s.db.Put(s.repo1.RefKey(""), NewPackageRefList().Encode()), IsNil)
 
 	collection := NewPublishedRepoCollection(s.db)
 	repo, err := collection.ByStoragePrefixDistribution("", "ppa", "anaconda")
@@ -651,7 +655,7 @@ func (s *PublishedRepoCollectionSuite) TestLoadPre0_6(c *C) {
 }
 
 func (s *PublishedRepoCollectionSuite) TestForEachAndLen(c *C) {
-	s.collection.Add(s.repo1)
+	s.collection.Add(s.repo1, s.reflistCollection)
 
 	count := 0
 	err := s.collection.ForEach(func(*PublishedRepo) error {
@@ -672,17 +676,17 @@ func (s *PublishedRepoCollectionSuite) TestForEachAndLen(c *C) {
 }
 
 func (s *PublishedRepoCollectionSuite) TestBySnapshot(c *C) {
-	c.Check(s.collection.Add(s.repo1), IsNil)
-	c.Check(s.collection.Add(s.repo2), IsNil)
+	c.Check(s.collection.Add(s.repo1, s.reflistCollection), IsNil)
+	c.Check(s.collection.Add(s.repo2, s.reflistCollection), IsNil)
 
 	c.Check(s.collection.BySnapshot(s.snap1), DeepEquals, []*PublishedRepo{s.repo1, s.repo2})
 	c.Check(s.collection.BySnapshot(s.snap2), DeepEquals, []*PublishedRepo{s.repo2})
 }
 
 func (s *PublishedRepoCollectionSuite) TestByLocalRepo(c *C) {
-	c.Check(s.collection.Add(s.repo1), IsNil)
-	c.Check(s.collection.Add(s.repo4), IsNil)
-	c.Check(s.collection.Add(s.repo5), IsNil)
+	c.Check(s.collection.Add(s.repo1, s.reflistCollection), IsNil)
+	c.Check(s.collection.Add(s.repo4, s.reflistCollection), IsNil)
+	c.Check(s.collection.Add(s.repo5, s.reflistCollection), IsNil)
 
 	c.Check(s.collection.ByLocalRepo(s.localRepo), DeepEquals, []*PublishedRepo{s.repo4, s.repo5})
 }
@@ -692,10 +696,10 @@ func (s *PublishedRepoCollectionSuite) TestListReferencedFiles(c *C) {
 	c.Check(s.factory.PackageCollection().Update(s.p2), IsNil)
 	c.Check(s.factory.PackageCollection().Update(s.p3), IsNil)
 
-	c.Check(s.collection.Add(s.repo1), IsNil)
-	c.Check(s.collection.Add(s.repo2), IsNil)
-	c.Check(s.collection.Add(s.repo4), IsNil)
-	c.Check(s.collection.Add(s.repo5), IsNil)
+	c.Check(s.collection.Add(s.repo1, s.reflistCollection), IsNil)
+	c.Check(s.collection.Add(s.repo2, s.reflistCollection), IsNil)
+	c.Check(s.collection.Add(s.repo4, s.reflistCollection), IsNil)
+	c.Check(s.collection.Add(s.repo5, s.reflistCollection), IsNil)
 
 	files, err := s.collection.listReferencedFilesByComponent(".", []string{"main", "contrib"}, s.factory, nil)
 	c.Assert(err, IsNil)
@@ -711,12 +715,12 @@ func (s *PublishedRepoCollectionSuite) TestListReferencedFiles(c *C) {
 	})
 
 	snap3 := NewSnapshotFromRefList("snap3", []*Snapshot{}, s.snap2.RefList(), "desc3")
-	s.snapshotCollection.Add(snap3)
+	s.snapshotCollection.Add(snap3, s.reflistCollection)
 
 	// Ensure that adding a second publish point with matching files doesn't give duplicate results.
 	repo3, err := NewPublishedRepo("", "", "anaconda-2", []string{}, []string{"main"}, []interface{}{snap3}, s.factory)
 	c.Check(err, IsNil)
-	c.Check(s.collection.Add(repo3), IsNil)
+	c.Check(s.collection.Add(repo3, s.reflistCollection), IsNil)
 
 	files, err = s.collection.listReferencedFilesByComponent(".", []string{"main", "contrib"}, s.factory, nil)
 	c.Assert(err, IsNil)
@@ -737,6 +741,7 @@ type PublishedRepoRemoveSuite struct {
 	db                                  database.Storage
 	factory                             *CollectionFactory
 	snapshotCollection                  *SnapshotCollection
+	reflistCollection                   *RefListCollection
 	collection                          *PublishedRepoCollection
 	root, root2                         string
 	provider                            *FakeStorageProvider
@@ -752,10 +757,11 @@ func (s *PublishedRepoRemoveSuite) SetUpTest(c *C) {
 	s.factory = NewCollectionFactory(s.db)
 
 	s.snapshotCollection = s.factory.SnapshotCollection()
+	s.reflistCollection = s.factory.RefListCollection()
 
 	s.snap1 = NewSnapshotFromPackageList("snap1", []*Snapshot{}, NewPackageList(), "desc1")
 
-	s.snapshotCollection.Add(s.snap1)
+	s.snapshotCollection.Add(s.snap1, s.reflistCollection)
 
 	s.repo1, _ = NewPublishedRepo("", "ppa", "anaconda", []string{}, []string{"main"}, []interface{}{s.snap1}, s.factory)
 	s.repo2, _ = NewPublishedRepo("", "", "anaconda", []string{}, []string{"main"}, []interface{}{s.snap1}, s.factory)
@@ -764,11 +770,11 @@ func (s *PublishedRepoRemoveSuite) SetUpTest(c *C) {
 	s.repo5, _ = NewPublishedRepo("files:other", "ppa", "osminog", []string{}, []string{"contrib"}, []interface{}{s.snap1}, s.factory)
 
 	s.collection = s.factory.PublishedRepoCollection()
-	s.collection.Add(s.repo1)
-	s.collection.Add(s.repo2)
-	s.collection.Add(s.repo3)
-	s.collection.Add(s.repo4)
-	s.collection.Add(s.repo5)
+	s.collection.Add(s.repo1, s.reflistCollection)
+	s.collection.Add(s.repo2, s.reflistCollection)
+	s.collection.Add(s.repo3, s.reflistCollection)
+	s.collection.Add(s.repo4, s.reflistCollection)
+	s.collection.Add(s.repo5, s.reflistCollection)
 
 	s.root = c.MkDir()
 	s.publishedStorage = files.NewPublishedStorage(s.root, "", "")
diff --git a/deb/reflist.go b/deb/reflist.go
index 30396548c..df1b9b2e6 100644
--- a/deb/reflist.go
+++ b/deb/reflist.go
@@ -2,10 +2,15 @@ package deb
 
 import (
 	"bytes"
+	"crypto/sha256"
+	"encoding/base64"
 	"encoding/json"
+	"fmt"
 	"sort"
 
 	"github.com/AlekSi/pointer"
+	"github.com/aptly-dev/aptly/database"
+	"github.com/cespare/xxhash/v2"
 	"github.com/ugorji/go/codec"
 )
 
@@ -44,6 +49,13 @@ func NewPackageRefListFromPackageList(list *PackageList) *PackageRefList {
 	return reflist
 }
 
+func (l *PackageRefList) Clone() *PackageRefList {
+	clone := &PackageRefList{}
+	clone.Refs = make([][]byte, l.Len())
+	copy(clone.Refs, l.Refs)
+	return clone
+}
+
 // Len returns number of refs
 func (l *PackageRefList) Len() int {
 	return len(l.Refs)
@@ -184,8 +196,12 @@ func (d PackageDiff) MarshalJSON() ([]byte, error) {
 type PackageDiffs []PackageDiff
 
 // Diff calculates difference between two reflists
-func (l *PackageRefList) Diff(r *PackageRefList, packageCollection *PackageCollection) (result PackageDiffs, err error) {
-	result = make(PackageDiffs, 0, 128)
+func (l *PackageRefList) Diff(r *PackageRefList, packageCollection *PackageCollection, result PackageDiffs) (PackageDiffs, error) {
+	var err error
+
+	if result == nil {
+		result = make(PackageDiffs, 0, 128)
+	}
 
 	// pointer to left and right reflists
 	il, ir := 0, 0
@@ -258,7 +274,7 @@ func (l *PackageRefList) Diff(r *PackageRefList, packageCollection *PackageColle
 		}
 	}
 
-	return
+	return result, nil
 }
 
 // Merge merges reflist r into current reflist. If overrideMatching, merge
@@ -391,3 +407,773 @@ func (l *PackageRefList) FilterLatestRefs() {
 		lastArch, lastName, lastVer = arch, name, ver
 	}
 }
+
+const (
+	reflistBucketCount = 1 << 6
+	reflistBucketMask  = reflistBucketCount - 1
+)
+
+type reflistDigestArray [sha256.Size]byte
+
+func bucketRefPrefix(ref []byte) []byte {
+	const maxPrefixLen = 3
+
+	// Cut out the arch, leaving behind the package name and subsequent info.
+	_, ref, _ = bytes.Cut(ref, []byte{' '})
+
+	// Strip off the lib prefix, so that "libxyz" and "xyz", which are likely
+	// to be updated together, go in the same bucket.
+	libPrefix := []byte("lib")
+	if bytes.HasPrefix(ref, libPrefix) {
+		ref = ref[len(libPrefix):]
+	}
+
+	prefixLen := len(ref)
+	if maxPrefixLen < prefixLen {
+		prefixLen = maxPrefixLen
+	}
+	prefix, _, _ := bytes.Cut(ref[:prefixLen], []byte{' '})
+	return prefix
+}
+
+func bucketIdxForRef(ref []byte) int {
+	return int(xxhash.Sum64(bucketRefPrefix(ref))) & reflistBucketMask
+}
+
+// SplitRefList is a list of package refs, similar to a PackageRefList. However,
+// instead of storing a linear array of refs, SplitRefList splits the refs into
+// PackageRefList "buckets", based on a hash of the package name inside the ref.
+// Each bucket has a digest of its contents that serves as its key in the database.
+//
+// When serialized, a SplitRefList just becomes an array of bucket digests, and
+// the buckets themselves are stored separately. Because the buckets are then
+// referenced by their digests, multiple independent reflists can share buckets,
+// if their buckets have matching digests.
+//
+// Buckets themselves may not be confirmed to a single database value; instead,
+// they're split into "segments", based on the database's preferred maximum
+// value size. This prevents large buckets from slowing down the database.
+type SplitRefList struct {
+	Buckets [][]byte
+
+	bucketRefs []*PackageRefList
+}
+
+// NewSplitRefList creates empty SplitRefList
+func NewSplitRefList() *SplitRefList {
+	sl := &SplitRefList{}
+	sl.reset()
+	return sl
+}
+
+// NewSplitRefListFromRefList creates SplitRefList from PackageRefList
+func NewSplitRefListFromRefList(reflist *PackageRefList) *SplitRefList {
+	sl := NewSplitRefList()
+	sl.Replace(reflist)
+	return sl
+}
+
+// NewSplitRefListFromRefList creates SplitRefList from PackageList
+func NewSplitRefListFromPackageList(list *PackageList) *SplitRefList {
+	return NewSplitRefListFromRefList(NewPackageRefListFromPackageList(list))
+}
+
+func (sl *SplitRefList) reset() {
+	sl.Buckets = make([][]byte, reflistBucketCount)
+	sl.bucketRefs = make([]*PackageRefList, reflistBucketCount)
+}
+
+// Has checks whether package is part of reflist
+func (sl *SplitRefList) Has(p *Package) bool {
+	idx := bucketIdxForRef(p.Key(""))
+	if bucket := sl.bucketRefs[idx]; bucket != nil {
+		return bucket.Has(p)
+	}
+	return false
+}
+
+// Len returns number of refs
+func (sl *SplitRefList) Len() int {
+	total := 0
+	for _, bucket := range sl.bucketRefs {
+		if bucket != nil {
+			total += bucket.Len()
+		}
+	}
+	return total
+}
+
+func reflistDigest(l *PackageRefList) []byte {
+	// Different algorithms on PackageRefLists will sometimes return a nil slice
+	// of refs and other times return an empty slice. Regardless, they should
+	// both be treated identically and be given an empty digest.
+	if len(l.Refs) == 0 {
+		return nil
+	}
+
+	h := sha256.New()
+	for _, ref := range l.Refs {
+		h.Write(ref)
+		h.Write([]byte{0})
+	}
+	return h.Sum(nil)
+}
+
+// Removes all the refs inside and replaces them with those in the given reflist
+func (sl *SplitRefList) Replace(reflist *PackageRefList) {
+	sl.reset()
+
+	for _, ref := range reflist.Refs {
+		idx := bucketIdxForRef(ref)
+
+		bucket := sl.bucketRefs[idx]
+		if bucket == nil {
+			bucket = NewPackageRefList()
+			sl.bucketRefs[idx] = bucket
+		}
+
+		bucket.Refs = append(bucket.Refs, ref)
+	}
+
+	for idx, bucket := range sl.bucketRefs {
+		if bucket != nil {
+			sort.Sort(bucket)
+			sl.Buckets[idx] = reflistDigest(bucket)
+		}
+	}
+}
+
+// Merge merges reflist r into current reflist (see PackageRefList.Merge)
+func (sl *SplitRefList) Merge(r *SplitRefList, overrideMatching, ignoreConflicting bool) (result *SplitRefList) {
+	result = NewSplitRefList()
+
+	var empty PackageRefList
+	for idx, lbucket := range sl.bucketRefs {
+		rbucket := r.bucketRefs[idx]
+		if lbucket == nil && rbucket == nil {
+			continue
+		}
+
+		if lbucket == nil {
+			lbucket = &empty
+		} else if rbucket == nil {
+			rbucket = &empty
+		}
+
+		result.bucketRefs[idx] = lbucket.Merge(rbucket, overrideMatching, ignoreConflicting)
+		result.Buckets[idx] = reflistDigest(result.bucketRefs[idx])
+	}
+
+	return
+}
+
+// Subtract returns all packages in l that are not in r
+func (sl *SplitRefList) Subtract(r *SplitRefList) (result *SplitRefList) {
+	result = NewSplitRefList()
+
+	for idx, lbucket := range sl.bucketRefs {
+		rbucket := r.bucketRefs[idx]
+		if lbucket != nil {
+			if rbucket != nil {
+				result.bucketRefs[idx] = lbucket.Subtract(rbucket)
+				result.Buckets[idx] = reflistDigest(result.bucketRefs[idx])
+			} else {
+				result.bucketRefs[idx] = lbucket.Clone()
+				result.Buckets[idx] = sl.Buckets[idx]
+			}
+		}
+	}
+
+	return
+}
+
+// Diff calculates difference between two reflists
+func (sl *SplitRefList) Diff(r *SplitRefList, packageCollection *PackageCollection, result PackageDiffs) (PackageDiffs, error) {
+	var err error
+
+	if result == nil {
+		result = make(PackageDiffs, 0, 128)
+	}
+
+	var empty PackageRefList
+	for idx, lbucket := range sl.bucketRefs {
+		rbucket := r.bucketRefs[idx]
+		if lbucket != nil {
+			if rbucket != nil {
+				result, err = lbucket.Diff(rbucket, packageCollection, result)
+			} else {
+				result, err = lbucket.Diff(&empty, packageCollection, result)
+			}
+		} else if rbucket != nil {
+			result, err = empty.Diff(rbucket, packageCollection, result)
+		}
+
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	sort.Slice(result, func(i, j int) bool {
+		var ri, rj []byte
+		if result[i].Left != nil {
+			ri = result[i].Left.Key("")
+		} else {
+			ri = result[i].Right.Key("")
+		}
+		if result[j].Left != nil {
+			rj = result[j].Left.Key("")
+		} else {
+			rj = result[j].Right.Key("")
+		}
+
+		return bytes.Compare(ri, rj) < 0
+	})
+
+	return result, nil
+}
+
+// FilterLatestRefs reduces a reflist to the latest of each package (see PackageRefList.FilterLatestRefs)
+func (sl *SplitRefList) FilterLatestRefs() {
+	for idx, bucket := range sl.bucketRefs {
+		if bucket != nil {
+			bucket.FilterLatestRefs()
+			sl.Buckets[idx] = reflistDigest(bucket)
+		}
+	}
+}
+
+// Flatten creates a flat PackageRefList containing all the refs in this reflist
+func (sl *SplitRefList) Flatten() *PackageRefList {
+	reflist := NewPackageRefList()
+	sl.ForEach(func(ref []byte) error {
+		reflist.Refs = append(reflist.Refs, ref)
+		return nil
+	})
+	sort.Sort(reflist)
+	return reflist
+}
+
+// ForEachBucket calls handler for each bucket in list
+func (sl *SplitRefList) ForEachBucket(handler func(digest []byte, bucket *PackageRefList) error) error {
+	for idx, digest := range sl.Buckets {
+		if len(digest) == 0 {
+			continue
+		}
+
+		bucket := sl.bucketRefs[idx]
+		if bucket != nil {
+			if err := handler(digest, bucket); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
+// ForEach calls handler for each package ref in list
+//
+// IMPORTANT: unlike PackageRefList.ForEach, the order of handler invocations
+// is *not* guaranteed to be sorted.
+func (sl *SplitRefList) ForEach(handler func([]byte) error) error {
+	for idx, digest := range sl.Buckets {
+		if len(digest) == 0 {
+			continue
+		}
+
+		bucket := sl.bucketRefs[idx]
+		if bucket != nil {
+			if err := bucket.ForEach(handler); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
+// RefListDigestSet is a set of SplitRefList bucket digests
+type RefListDigestSet struct {
+	items map[reflistDigestArray]struct{}
+}
+
+// NewRefListDigestSet creates empty RefListDigestSet
+func NewRefListDigestSet() *RefListDigestSet {
+	return &RefListDigestSet{items: map[reflistDigestArray]struct{}{}}
+}
+
+// Len returns number of digests in the set
+func (set *RefListDigestSet) Len() int {
+	return len(set.items)
+}
+
+// ForEach calls handler for each digest in the set
+func (set *RefListDigestSet) ForEach(handler func(digest []byte) error) error {
+	for digest := range set.items {
+		if err := handler(digest[:]); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// workaround for: conversion of slices to arrays requires go1.20 or later
+func newRefListArray(digest []byte) reflistDigestArray {
+	var array reflistDigestArray
+	copy(array[:], digest)
+	return array
+}
+
+// Add adds digest to set, doing nothing if the digest was already present
+func (set *RefListDigestSet) Add(digest []byte) {
+	set.items[newRefListArray(digest)] = struct{}{}
+}
+
+// AddAllInRefList adds all the bucket digests in a SplitRefList to the set
+func (set *RefListDigestSet) AddAllInRefList(sl *SplitRefList) {
+	for _, digest := range sl.Buckets {
+		if len(digest) > 0 {
+			set.Add(digest)
+		}
+	}
+}
+
+// Has checks whether a digest is part of set
+func (set *RefListDigestSet) Has(digest []byte) bool {
+	_, ok := set.items[newRefListArray(digest)]
+	return ok
+}
+
+// Remove removes a digest from set
+func (set *RefListDigestSet) Remove(digest []byte) {
+	delete(set.items, newRefListArray(digest))
+}
+
+// RemoveAll removes all the digests in other from the current set
+func (set *RefListDigestSet) RemoveAll(other *RefListDigestSet) {
+	for digest := range other.items {
+		delete(set.items, digest)
+	}
+}
+
+// RefListCollection does listing, updating/adding/deleting of SplitRefLists
+type RefListCollection struct {
+	db database.Storage
+
+	cache map[reflistDigestArray]*PackageRefList
+}
+
+// NewRefListCollection creates a RefListCollection
+func NewRefListCollection(db database.Storage) *RefListCollection {
+	return &RefListCollection{db: db, cache: make(map[reflistDigestArray]*PackageRefList)}
+}
+
+type reflistStorageFormat int
+
+const (
+	// (legacy format) all the refs are stored inline in a single value
+	reflistStorageFormatInline reflistStorageFormat = iota
+	// the refs are split into buckets that are stored externally from the value
+	reflistStorageFormatSplit
+)
+
+// NoPadding is used because all digests are the same length, so the padding
+// is useless and only serves to muddy the output.
+var bucketDigestEncoding = base64.StdEncoding.WithPadding(base64.NoPadding)
+
+func segmentPrefix(encodedDigest string) []byte {
+	return []byte(fmt.Sprintf("F%s-", encodedDigest))
+}
+
+// workaround for go 1.19 instead of bytes.Clone
+func cloneBytes(b []byte) []byte {
+	if b == nil {
+		return nil
+	}
+	cloned := make([]byte, len(b))
+	copy(cloned, b)
+	return cloned
+}
+
+func segmentIndexKey(prefix []byte, idx int) []byte {
+	// Assume most buckets won't have more than 0xFFFF = ~65k segments (which
+	// would be an extremely large bucket!).
+	return append(cloneBytes(prefix), []byte(fmt.Sprintf("%04x", idx))...)
+}
+
+// AllBucketDigests returns a set of all the bucket digests in the database
+func (collection *RefListCollection) AllBucketDigests() (*RefListDigestSet, error) {
+	digests := NewRefListDigestSet()
+
+	err := collection.db.ProcessByPrefix([]byte("F"), func(key []byte, _ []byte) error {
+		if !bytes.HasSuffix(key, []byte("-0000")) {
+			// Ignore additional segments for the same digest.
+			return nil
+		}
+
+		encodedDigest, _, foundDash := bytes.Cut(key[1:], []byte("-"))
+		if !foundDash {
+			return fmt.Errorf("invalid key: %s", string(key))
+		}
+		digest := make([]byte, bucketDigestEncoding.DecodedLen(len(encodedDigest)))
+		if _, err := bucketDigestEncoding.Decode(digest, encodedDigest); err != nil {
+			return fmt.Errorf("decoding key %s: %w", string(key), err)
+		}
+
+		digests.Add(digest)
+		return nil
+	})
+
+	if err != nil {
+		return nil, err
+	}
+	return digests, nil
+}
+
+// UnsafeDropBucket drops the bucket associated with digest from the database,
+// doing so inside batch
+//
+// This is considered "unsafe" because no checks are performed to ensure that
+// the bucket is no longer referenced by any saved reflists.
+func (collection *RefListCollection) UnsafeDropBucket(digest []byte, batch database.Batch) error {
+	prefix := segmentPrefix(bucketDigestEncoding.EncodeToString(digest))
+	return collection.db.ProcessByPrefix(prefix, func(key []byte, _ []byte) error {
+		return batch.Delete(key)
+	})
+}
+
+func (collection *RefListCollection) load(sl *SplitRefList, key []byte) (reflistStorageFormat, error) {
+	sl.reset()
+
+	data, err := collection.db.Get(key)
+	if err != nil {
+		return 0, err
+	}
+
+	var splitOrInlineRefList struct {
+		*SplitRefList
+		*PackageRefList
+	}
+	handle := &codec.MsgpackHandle{}
+	handle.ZeroCopy = true
+	decoder := codec.NewDecoderBytes(data, handle)
+	if err := decoder.Decode(&splitOrInlineRefList); err != nil {
+		return 0, err
+	}
+
+	if splitOrInlineRefList.SplitRefList != nil {
+		sl.Buckets = splitOrInlineRefList.Buckets
+	} else if splitOrInlineRefList.PackageRefList != nil {
+		sl.Replace(splitOrInlineRefList.PackageRefList)
+		return reflistStorageFormatInline, nil
+	}
+
+	return reflistStorageFormatSplit, nil
+}
+
+func (collection *RefListCollection) loadBuckets(sl *SplitRefList) error {
+	for idx := range sl.Buckets {
+		if sl.bucketRefs[idx] != nil {
+			continue
+		}
+
+		var bucket *PackageRefList
+
+		if digest := sl.Buckets[idx]; len(digest) > 0 {
+			cacheKey := newRefListArray(digest)
+			bucket = collection.cache[cacheKey]
+			if bucket == nil {
+				bucket = NewPackageRefList()
+				prefix := segmentPrefix(bucketDigestEncoding.EncodeToString(digest))
+				err := collection.db.ProcessByPrefix(prefix, func(_ []byte, value []byte) error {
+					var l PackageRefList
+					if err := l.Decode(append([]byte{}, value...)); err != nil {
+						return err
+					}
+
+					bucket.Refs = append(bucket.Refs, l.Refs...)
+					return nil
+				})
+
+				if err != nil {
+					return err
+				}
+
+				// The segments may not have been iterated in order, so make sure to re-sort
+				// here.
+				sort.Sort(bucket)
+				collection.cache[cacheKey] = bucket
+			}
+
+			actualDigest := reflistDigest(bucket)
+			if !bytes.Equal(actualDigest, digest) {
+				return fmt.Errorf("corrupt reflist bucket %d: expected digest %s, got %s",
+					idx,
+					bucketDigestEncoding.EncodeToString(digest),
+					bucketDigestEncoding.EncodeToString(actualDigest))
+			}
+		}
+
+		sl.bucketRefs[idx] = bucket
+	}
+
+	return nil
+}
+
+// LoadComplete loads the reflist stored at the given key, as well as all the
+// buckets referenced by a split reflist
+func (collection *RefListCollection) LoadComplete(sl *SplitRefList, key []byte) error {
+	if _, err := collection.load(sl, key); err != nil {
+		return err
+	}
+
+	return collection.loadBuckets(sl)
+}
+
+// RefListBatch is a wrapper over a database.Batch that tracks already-written
+// reflists to avoid writing them multiple times
+//
+// It is *not* safe to use the same underlying database.Batch that has already
+// been given to UnsafeDropBucket.
+type RefListBatch struct {
+	batch database.Batch
+
+	alreadyWritten *RefListDigestSet
+}
+
+// NewBatch creates a new RefListBatch wrapping the given database.Batch
+func (collection *RefListCollection) NewBatch(batch database.Batch) *RefListBatch {
+	return &RefListBatch{
+		batch:          batch,
+		alreadyWritten: NewRefListDigestSet(),
+	}
+}
+
+type reflistUpdateContext struct {
+	rb    *RefListBatch
+	stats *RefListMigrationStats
+}
+
+func clearSegmentRefs(reflist *PackageRefList, recommendedMaxKVSize int) {
+	avgRefsInSegment := recommendedMaxKVSize / 70
+	reflist.Refs = make([][]byte, 0, avgRefsInSegment)
+}
+
+func flushSegmentRefs(uctx *reflistUpdateContext, prefix []byte, segment int, reflist *PackageRefList) error {
+	encoded := reflist.Encode()
+	err := uctx.rb.batch.Put(segmentIndexKey(prefix, segment), encoded)
+	if err == nil && uctx.stats != nil {
+		uctx.stats.Segments++
+	}
+	return err
+}
+
+func (collection *RefListCollection) updateWithContext(sl *SplitRefList, key []byte, uctx *reflistUpdateContext) error {
+	if sl != nil {
+		recommendedMaxKVSize := collection.db.GetRecommendedMaxKVSize()
+
+		for idx, digest := range sl.Buckets {
+			if len(digest) == 0 {
+				continue
+			}
+
+			if uctx.rb.alreadyWritten.Has(digest) {
+				continue
+			}
+
+			prefix := segmentPrefix(bucketDigestEncoding.EncodeToString(digest))
+			if collection.db.HasPrefix(prefix) {
+				continue
+			}
+
+			// All the sizing information taken from the msgpack spec:
+			// https://github.com/msgpack/msgpack/blob/master/spec.md
+
+			// Assume that a segment will have [16,2^16) elements, which would
+			// fit into an array 16 and thus have 3 bytes of overhead.
+			// (A database would need a massive recommendedMaxKVSize to pass
+			// that limit.)
+			size := len(segmentIndexKey(prefix, 0)) + 3
+			segment := 0
+
+			var reflist PackageRefList
+			clearSegmentRefs(&reflist, recommendedMaxKVSize)
+			for _, ref := range sl.bucketRefs[idx].Refs {
+				// In order to determine the size of the ref in the database,
+				// we need to know how much overhead will be added with by msgpack
+				// encoding.
+				requiredSize := len(ref)
+				if requiredSize < 1<<5 {
+					requiredSize++
+				} else if requiredSize < 1<<8 {
+					requiredSize += 2
+				} else if requiredSize < 1<<16 {
+					requiredSize += 3
+				} else {
+					requiredSize += 4
+				}
+				if size+requiredSize > recommendedMaxKVSize {
+					if err := flushSegmentRefs(uctx, prefix, segment, &reflist); err != nil {
+						return err
+					}
+					clearSegmentRefs(&reflist, recommendedMaxKVSize)
+					segment++
+				}
+
+				reflist.Refs = append(reflist.Refs, ref)
+				size += requiredSize
+			}
+
+			if len(reflist.Refs) > 0 {
+				if err := flushSegmentRefs(uctx, prefix, segment, &reflist); err != nil {
+					return err
+				}
+			}
+
+			uctx.rb.alreadyWritten.Add(digest)
+			if uctx.stats != nil {
+				uctx.stats.Buckets++
+			}
+		}
+	}
+
+	var buf bytes.Buffer
+	encoder := codec.NewEncoder(&buf, &codec.MsgpackHandle{})
+	encoder.Encode(sl)
+	err := uctx.rb.batch.Put(key, buf.Bytes())
+	if err == nil && uctx.stats != nil {
+		uctx.stats.Reflists++
+	}
+	return err
+}
+
+// UpdateInBatch will save or update the SplitRefList at key, as well as save the buckets inside,
+// as part of the given batch
+func (collection *RefListCollection) UpdateInBatch(sl *SplitRefList, key []byte, batch *RefListBatch) error {
+	return collection.updateWithContext(sl, key, &reflistUpdateContext{rb: batch})
+}
+
+// Update will save or update the SplitRefList at key, as well as save the buckets inside
+func (collection *RefListCollection) Update(sl *SplitRefList, key []byte) error {
+	rb := collection.NewBatch(collection.db.CreateBatch())
+	err := collection.UpdateInBatch(sl, key, rb)
+	if err == nil {
+		err = rb.batch.Write()
+	}
+	return err
+}
+
+// RefListMigrationStats counts a number of reflists, buckets, and segments
+type RefListMigrationStats struct {
+	Reflists, Buckets, Segments int
+}
+
+// RefListMigration wraps a RefListBatch for the purpose of migrating inline format
+// reflists to split reflists
+//
+// Once the batch gets too large, it will automatically be flushed to the database,
+// and a new batch will be created in its place.
+type RefListMigration struct {
+	rb *RefListBatch
+
+	dryRun bool
+
+	// current number of reflists/buckets/segments queued in the current, unwritten batch
+	batchStats RefListMigrationStats
+	flushStats RefListMigrationStats
+}
+
+// NewMigration creates an empty RefListMigration
+func (collection *RefListCollection) NewMigration() *RefListMigration {
+	return &RefListMigration{}
+}
+
+// NewMigrationDryRun creates an empty RefListMigration that will track the
+// changes to make as usual but avoid actually writing to the db
+func (collection *RefListCollection) NewMigrationDryRun() *RefListMigration {
+	return &RefListMigration{dryRun: true}
+}
+
+// Stats returns statistics on the written values in the current migration
+func (migration *RefListMigration) Stats() RefListMigrationStats {
+	return migration.flushStats
+}
+
+// Flush will flush the current batch in the migration to the database
+func (migration *RefListMigration) Flush() error {
+	if migration.batchStats.Segments > 0 {
+		if !migration.dryRun {
+			if err := migration.rb.batch.Write(); err != nil {
+				return err
+			}
+
+			// It's important that we don't clear the batch on dry runs, because
+			// the batch is what contains the list of already-written buckets.
+			// If we're not writing to the database, and we clear that list,
+			// duplicate "writes" will occur.
+			migration.rb = nil
+		}
+
+		migration.flushStats.Reflists += migration.batchStats.Reflists
+		migration.flushStats.Buckets += migration.batchStats.Buckets
+		migration.flushStats.Segments += migration.batchStats.Segments
+		migration.batchStats = RefListMigrationStats{}
+	}
+
+	return nil
+}
+
+// LoadCompleteAndMigrate will load the reflist and its buckets as RefListCollection.LoadComplete,
+// migrating any inline reflists to split ones along the way
+func (collection *RefListCollection) LoadCompleteAndMigrate(sl *SplitRefList, key []byte, migration *RefListMigration) error {
+	// Given enough reflists, the memory used by a batch starts to become massive, so
+	// make sure to flush the written segments periodically. Note that this is only
+	// checked *after* a migration of a full bucket (and all the segments inside)
+	// takes place, as splitting a single bucket write into multiple batches would
+	// be unsafe if an interruption occurs midway.
+	const maxMigratorBatch = 50000
+
+	format, err := collection.load(sl, key)
+	if err != nil {
+		return err
+	}
+
+	switch format {
+	case reflistStorageFormatInline:
+		if migration.rb == nil {
+			migration.rb = collection.NewBatch(collection.db.CreateBatch())
+		}
+
+		collection.updateWithContext(sl, key, &reflistUpdateContext{
+			rb:    migration.rb,
+			stats: &migration.batchStats,
+		})
+
+		if migration.batchStats.Segments > maxMigratorBatch {
+			if err := migration.Flush(); err != nil {
+				return err
+			}
+		}
+
+		return nil
+	case reflistStorageFormatSplit:
+		return collection.loadBuckets(sl)
+	default:
+		panic(fmt.Sprintf("unexpected format %v", format))
+	}
+}
+
+// AnyRefList is implemented by both PackageRefList and SplitRefList
+type AnyRefList interface {
+	Has(p *Package) bool
+	Len() int
+	ForEach(handler func([]byte) error) error
+	FilterLatestRefs()
+}
+
+// Check interface
+var (
+	_ AnyRefList = (*PackageRefList)(nil)
+	_ AnyRefList = (*SplitRefList)(nil)
+)
diff --git a/deb/reflist_bench_test.go b/deb/reflist_bench_test.go
index b377574ce..f81a84d0a 100644
--- a/deb/reflist_bench_test.go
+++ b/deb/reflist_bench_test.go
@@ -45,3 +45,41 @@ func BenchmarkReflistDecode(b *testing.B) {
 		(&PackageRefList{}).Decode(data)
 	}
 }
+
+func BenchmarkSplitRefListCreationSmall(b *testing.B) {
+	const count = 400
+
+	l := NewPackageRefList()
+
+	for i := 0; i < count; i++ {
+		l.Refs = append(l.Refs, []byte(fmt.Sprintf("Pamd64 %x %d", i, i)))
+	}
+
+	sort.Sort(l)
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		for j := 0; j < 8; j++ {
+			NewSplitRefListFromRefList(l)
+		}
+	}
+}
+
+func BenchmarkSplitRefListCreationLarge(b *testing.B) {
+	const count = 4096
+
+	l := NewPackageRefList()
+
+	for i := 0; i < count; i++ {
+		l.Refs = append(l.Refs, []byte(fmt.Sprintf("Pamd64 %x %d", i, i)))
+	}
+
+	sort.Sort(l)
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		for j := 0; j < 8; j++ {
+			NewSplitRefListFromRefList(l)
+		}
+	}
+}
diff --git a/deb/reflist_test.go b/deb/reflist_test.go
index ec7ed09f7..bfc641131 100644
--- a/deb/reflist_test.go
+++ b/deb/reflist_test.go
@@ -1,7 +1,10 @@
 package deb
 
 import (
+	"bytes"
+	"encoding/hex"
 	"errors"
+	"fmt"
 
 	"github.com/aptly-dev/aptly/database/goleveldb"
 
@@ -9,24 +12,83 @@ import (
 )
 
 type PackageRefListSuite struct {
-	// Simple list with "real" packages from stanzas
-	list                   *PackageList
 	p1, p2, p3, p4, p5, p6 *Package
 }
 
 var _ = Suite(&PackageRefListSuite{})
 
-func toStrSlice(reflist *PackageRefList) (result []string) {
+func verifyRefListIntegrity(c *C, rl AnyRefList) AnyRefList {
+	if rl, ok := rl.(*SplitRefList); ok {
+		for idx, bucket := range rl.bucketRefs {
+			if bucket == nil {
+				bucket = NewPackageRefList()
+			}
+			c.Check(rl.Buckets[idx], DeepEquals, reflistDigest(bucket))
+		}
+	}
+
+	return rl
+}
+
+func getRefs(rl AnyRefList) (refs [][]byte) {
+	switch rl := rl.(type) {
+	case *PackageRefList:
+		refs = rl.Refs
+	case *SplitRefList:
+		refs = rl.Flatten().Refs
+	default:
+		panic(fmt.Sprintf("unexpected reflist type %t", rl))
+	}
+
+	// Hack so that passing getRefs-returned slices to DeepEquals won't fail given a nil
+	// slice and an empty slice.
+	if len(refs) == 0 {
+		refs = nil
+	}
+	return
+}
+
+func toStrSlice(reflist AnyRefList) (result []string) {
 	result = make([]string, reflist.Len())
-	for i, r := range reflist.Refs {
+	for i, r := range getRefs(reflist) {
 		result[i] = string(r)
 	}
 	return
 }
 
-func (s *PackageRefListSuite) SetUpTest(c *C) {
-	s.list = NewPackageList()
+type reflistFactory struct {
+	new                func() AnyRefList
+	newFromRefs        func(refs ...[]byte) AnyRefList
+	newFromPackageList func(list *PackageList) AnyRefList
+}
+
+func forEachRefList(test func(f reflistFactory)) {
+	test(reflistFactory{
+		new: func() AnyRefList {
+			return NewPackageRefList()
+		},
+		newFromRefs: func(refs ...[]byte) AnyRefList {
+			return &PackageRefList{Refs: refs}
+		},
+		newFromPackageList: func(list *PackageList) AnyRefList {
+			return NewPackageRefListFromPackageList(list)
+		},
+	})
 
+	test(reflistFactory{
+		new: func() AnyRefList {
+			return NewSplitRefList()
+		},
+		newFromRefs: func(refs ...[]byte) AnyRefList {
+			return NewSplitRefListFromRefList(&PackageRefList{Refs: refs})
+		},
+		newFromPackageList: func(list *PackageList) AnyRefList {
+			return NewSplitRefListFromPackageList(list)
+		},
+	})
+}
+
+func (s *PackageRefListSuite) SetUpTest(c *C) {
 	s.p1 = NewPackageFromControlFile(packageStanza.Copy())
 	s.p2 = NewPackageFromControlFile(packageStanza.Copy())
 	stanza := packageStanza.Copy()
@@ -44,346 +106,600 @@ func (s *PackageRefListSuite) SetUpTest(c *C) {
 }
 
 func (s *PackageRefListSuite) TestNewPackageListFromRefList(c *C) {
-	db, _ := goleveldb.NewOpenDB(c.MkDir())
-	coll := NewPackageCollection(db)
-	coll.Update(s.p1)
-	coll.Update(s.p3)
+	forEachRefList(func(f reflistFactory) {
+		list := NewPackageList()
 
-	s.list.Add(s.p1)
-	s.list.Add(s.p3)
-	s.list.Add(s.p5)
-	s.list.Add(s.p6)
+		db, _ := goleveldb.NewOpenDB(c.MkDir())
+		coll := NewPackageCollection(db)
+		coll.Update(s.p1)
+		coll.Update(s.p3)
 
-	reflist := NewPackageRefListFromPackageList(s.list)
+		list.Add(s.p1)
+		list.Add(s.p3)
+		list.Add(s.p5)
+		list.Add(s.p6)
 
-	_, err := NewPackageListFromRefList(reflist, coll, nil)
-	c.Assert(err, ErrorMatches, "unable to load package with key.*")
+		reflist := f.newFromPackageList(list)
 
-	coll.Update(s.p5)
-	coll.Update(s.p6)
+		_, err := NewPackageListFromRefList(reflist, coll, nil)
+		c.Assert(err, ErrorMatches, "unable to load package with key.*")
 
-	list, err := NewPackageListFromRefList(reflist, coll, nil)
-	c.Assert(err, IsNil)
-	c.Check(list.Len(), Equals, 4)
-	c.Check(list.Add(s.p4), ErrorMatches, "conflict in package.*")
+		coll.Update(s.p5)
+		coll.Update(s.p6)
 
-	list, err = NewPackageListFromRefList(nil, coll, nil)
-	c.Assert(err, IsNil)
-	c.Check(list.Len(), Equals, 0)
+		list, err = NewPackageListFromRefList(reflist, coll, nil)
+		c.Assert(err, IsNil)
+		c.Check(list.Len(), Equals, 4)
+		c.Check(list.Add(s.p4), ErrorMatches, "conflict in package.*")
+
+		list, err = NewPackageListFromRefList(nil, coll, nil)
+		c.Assert(err, IsNil)
+		c.Check(list.Len(), Equals, 0)
+	})
 }
 
 func (s *PackageRefListSuite) TestNewPackageRefList(c *C) {
-	s.list.Add(s.p1)
-	s.list.Add(s.p3)
-	s.list.Add(s.p5)
-	s.list.Add(s.p6)
-
-	reflist := NewPackageRefListFromPackageList(s.list)
-	c.Assert(reflist.Len(), Equals, 4)
-	c.Check(reflist.Refs[0], DeepEquals, []byte(s.p1.Key("")))
-	c.Check(reflist.Refs[1], DeepEquals, []byte(s.p6.Key("")))
-	c.Check(reflist.Refs[2], DeepEquals, []byte(s.p5.Key("")))
-	c.Check(reflist.Refs[3], DeepEquals, []byte(s.p3.Key("")))
-
-	reflist = NewPackageRefList()
-	c.Check(reflist.Len(), Equals, 0)
+	forEachRefList(func(f reflistFactory) {
+		list := NewPackageList()
+		list.Add(s.p1)
+		list.Add(s.p3)
+		list.Add(s.p5)
+		list.Add(s.p6)
+
+		reflist := f.newFromPackageList(list)
+		verifyRefListIntegrity(c, reflist)
+		c.Assert(reflist.Len(), Equals, 4)
+		refs := getRefs(reflist)
+		c.Check(refs[0], DeepEquals, []byte(s.p1.Key("")))
+		c.Check(refs[1], DeepEquals, []byte(s.p6.Key("")))
+		c.Check(refs[2], DeepEquals, []byte(s.p5.Key("")))
+		c.Check(refs[3], DeepEquals, []byte(s.p3.Key("")))
+
+		reflist = f.new()
+		c.Check(reflist.Len(), Equals, 0)
+	})
 }
 
-func (s *PackageRefListSuite) TestPackageRefListEncodeDecode(c *C) {
-	s.list.Add(s.p1)
-	s.list.Add(s.p3)
-	s.list.Add(s.p5)
-	s.list.Add(s.p6)
+func (s *PackageRefListSuite) TestPackageRefListForeach(c *C) {
+	forEachRefList(func(f reflistFactory) {
+		list := NewPackageList()
+		list.Add(s.p1)
+		list.Add(s.p3)
+		list.Add(s.p5)
+		list.Add(s.p6)
 
-	reflist := NewPackageRefListFromPackageList(s.list)
+		reflist := f.newFromPackageList(list)
 
-	reflist2 := &PackageRefList{}
-	err := reflist2.Decode(reflist.Encode())
-	c.Assert(err, IsNil)
-	c.Check(reflist2.Len(), Equals, reflist.Len())
-	c.Check(reflist2.Refs, DeepEquals, reflist.Refs)
-}
+		Len := 0
+		err := reflist.ForEach(func([]byte) error {
+			Len++
+			return nil
+		})
 
-func (s *PackageRefListSuite) TestPackageRefListForeach(c *C) {
-	s.list.Add(s.p1)
-	s.list.Add(s.p3)
-	s.list.Add(s.p5)
-	s.list.Add(s.p6)
+		c.Check(Len, Equals, 4)
+		c.Check(err, IsNil)
 
-	reflist := NewPackageRefListFromPackageList(s.list)
+		e := errors.New("b")
 
-	Len := 0
-	err := reflist.ForEach(func([]byte) error {
-		Len++
-		return nil
-	})
-
-	c.Check(Len, Equals, 4)
-	c.Check(err, IsNil)
+		err = reflist.ForEach(func([]byte) error {
+			return e
+		})
 
-	e := errors.New("b")
+		c.Check(err, Equals, e)
+	})
+}
 
-	err = reflist.ForEach(func([]byte) error {
-		return e
+func (s *PackageRefListSuite) TestHas(c *C) {
+	forEachRefList(func(f reflistFactory) {
+		list := NewPackageList()
+		list.Add(s.p1)
+		list.Add(s.p3)
+		list.Add(s.p5)
+		reflist := f.newFromPackageList(list)
+
+		c.Check(reflist.Has(s.p1), Equals, true)
+		c.Check(reflist.Has(s.p3), Equals, true)
+		c.Check(reflist.Has(s.p5), Equals, true)
+		c.Check(reflist.Has(s.p2), Equals, true)
+		c.Check(reflist.Has(s.p6), Equals, false)
 	})
+}
 
-	c.Check(err, Equals, e)
+func subtractRefLists(l, r AnyRefList) AnyRefList {
+	switch l := l.(type) {
+	case *PackageRefList:
+		return l.Subtract(r.(*PackageRefList))
+	case *SplitRefList:
+		return l.Subtract(r.(*SplitRefList))
+	default:
+		panic(fmt.Sprintf("unexpected reflist type %t", l))
+	}
 }
 
-func (s *PackageRefListSuite) TestHas(c *C) {
-	s.list.Add(s.p1)
-	s.list.Add(s.p3)
-	s.list.Add(s.p5)
-	reflist := NewPackageRefListFromPackageList(s.list)
-
-	c.Check(reflist.Has(s.p1), Equals, true)
-	c.Check(reflist.Has(s.p3), Equals, true)
-	c.Check(reflist.Has(s.p5), Equals, true)
-	c.Check(reflist.Has(s.p2), Equals, true)
-	c.Check(reflist.Has(s.p6), Equals, false)
+func (s *PackageRefListSuite) TestSubtract(c *C) {
+	forEachRefList(func(f reflistFactory) {
+		r1 := []byte("Pall r1")
+		r2 := []byte("Pall r2")
+		r3 := []byte("Pall r3")
+		r4 := []byte("Pall r4")
+		r5 := []byte("Pall r5")
+
+		empty := f.newFromRefs()
+		l1 := f.newFromRefs(r1, r2, r3, r4)
+		l2 := f.newFromRefs(r1, r3)
+		l3 := f.newFromRefs(r2, r4)
+		l4 := f.newFromRefs(r4, r5)
+		l5 := f.newFromRefs(r1, r2, r3)
+
+		c.Check(getRefs(subtractRefLists(l1, empty)), DeepEquals, getRefs(l1))
+		c.Check(getRefs(subtractRefLists(l1, l2)), DeepEquals, getRefs(l3))
+		c.Check(getRefs(subtractRefLists(l1, l3)), DeepEquals, getRefs(l2))
+		c.Check(getRefs(subtractRefLists(l1, l4)), DeepEquals, getRefs(l5))
+		c.Check(getRefs(subtractRefLists(empty, l1)), DeepEquals, getRefs(empty))
+		c.Check(getRefs(subtractRefLists(l2, l3)), DeepEquals, getRefs(l2))
+	})
 }
 
-func (s *PackageRefListSuite) TestSubstract(c *C) {
-	r1 := []byte("r1")
-	r2 := []byte("r2")
-	r3 := []byte("r3")
-	r4 := []byte("r4")
-	r5 := []byte("r5")
-
-	empty := &PackageRefList{Refs: [][]byte{}}
-	l1 := &PackageRefList{Refs: [][]byte{r1, r2, r3, r4}}
-	l2 := &PackageRefList{Refs: [][]byte{r1, r3}}
-	l3 := &PackageRefList{Refs: [][]byte{r2, r4}}
-	l4 := &PackageRefList{Refs: [][]byte{r4, r5}}
-	l5 := &PackageRefList{Refs: [][]byte{r1, r2, r3}}
-
-	c.Check(l1.Subtract(empty), DeepEquals, l1)
-	c.Check(l1.Subtract(l2), DeepEquals, l3)
-	c.Check(l1.Subtract(l3), DeepEquals, l2)
-	c.Check(l1.Subtract(l4), DeepEquals, l5)
-	c.Check(empty.Subtract(l1), DeepEquals, empty)
-	c.Check(l2.Subtract(l3), DeepEquals, l2)
+func diffRefLists(l, r AnyRefList, packageCollection *PackageCollection) (PackageDiffs, error) {
+	switch l := l.(type) {
+	case *PackageRefList:
+		return l.Diff(r.(*PackageRefList), packageCollection, nil)
+	case *SplitRefList:
+		return l.Diff(r.(*SplitRefList), packageCollection, nil)
+	default:
+		panic(fmt.Sprintf("unexpected reflist type %t", l))
+	}
 }
 
 func (s *PackageRefListSuite) TestDiff(c *C) {
-	db, _ := goleveldb.NewOpenDB(c.MkDir())
-	coll := NewPackageCollection(db)
-
-	packages := []*Package{
-		{Name: "lib", Version: "1.0", Architecture: "i386"},      //0
-		{Name: "dpkg", Version: "1.7", Architecture: "i386"},     //1
-		{Name: "data", Version: "1.1~bp1", Architecture: "all"},  //2
-		{Name: "app", Version: "1.1~bp1", Architecture: "i386"},  //3
-		{Name: "app", Version: "1.1~bp2", Architecture: "i386"},  //4
-		{Name: "app", Version: "1.1~bp2", Architecture: "amd64"}, //5
-		{Name: "xyz", Version: "3.0", Architecture: "sparc"},     //6
-	}
+	forEachRefList(func(f reflistFactory) {
+		db, _ := goleveldb.NewOpenDB(c.MkDir())
+		coll := NewPackageCollection(db)
+
+		packages := []*Package{
+			{Name: "lib", Version: "1.0", Architecture: "i386"},      //0
+			{Name: "dpkg", Version: "1.7", Architecture: "i386"},     //1
+			{Name: "data", Version: "1.1~bp1", Architecture: "all"},  //2
+			{Name: "app", Version: "1.1~bp1", Architecture: "i386"},  //3
+			{Name: "app", Version: "1.1~bp2", Architecture: "i386"},  //4
+			{Name: "app", Version: "1.1~bp2", Architecture: "amd64"}, //5
+			{Name: "xyz", Version: "3.0", Architecture: "sparc"},     //6
+		}
+
+		for _, p := range packages {
+			coll.Update(p)
+		}
+
+		listA := NewPackageList()
+		listA.Add(packages[0])
+		listA.Add(packages[1])
+		listA.Add(packages[2])
+		listA.Add(packages[3])
+		listA.Add(packages[6])
+
+		listB := NewPackageList()
+		listB.Add(packages[0])
+		listB.Add(packages[2])
+		listB.Add(packages[4])
+		listB.Add(packages[5])
+
+		reflistA := f.newFromPackageList(listA)
+		reflistB := f.newFromPackageList(listB)
+
+		diffAA, err := diffRefLists(reflistA, reflistA, coll)
+		c.Check(err, IsNil)
+		c.Check(diffAA, HasLen, 0)
+
+		diffAB, err := diffRefLists(reflistA, reflistB, coll)
+		c.Check(err, IsNil)
+		c.Check(diffAB, HasLen, 4)
+
+		c.Check(diffAB[0].Left, IsNil)
+		c.Check(diffAB[0].Right.String(), Equals, "app_1.1~bp2_amd64")
+
+		c.Check(diffAB[1].Left.String(), Equals, "app_1.1~bp1_i386")
+		c.Check(diffAB[1].Right.String(), Equals, "app_1.1~bp2_i386")
+
+		c.Check(diffAB[2].Left.String(), Equals, "dpkg_1.7_i386")
+		c.Check(diffAB[2].Right, IsNil)
+
+		c.Check(diffAB[3].Left.String(), Equals, "xyz_3.0_sparc")
+		c.Check(diffAB[3].Right, IsNil)
+
+		diffBA, err := diffRefLists(reflistB, reflistA, coll)
+		c.Check(err, IsNil)
+		c.Check(diffBA, HasLen, 4)
+
+		c.Check(diffBA[0].Right, IsNil)
+		c.Check(diffBA[0].Left.String(), Equals, "app_1.1~bp2_amd64")
+
+		c.Check(diffBA[1].Right.String(), Equals, "app_1.1~bp1_i386")
+		c.Check(diffBA[1].Left.String(), Equals, "app_1.1~bp2_i386")
+
+		c.Check(diffBA[2].Right.String(), Equals, "dpkg_1.7_i386")
+		c.Check(diffBA[2].Left, IsNil)
+
+		c.Check(diffBA[3].Right.String(), Equals, "xyz_3.0_sparc")
+		c.Check(diffBA[3].Left, IsNil)
+	})
+}
 
-	for _, p := range packages {
-		coll.Update(p)
-	}
+func (s *PackageRefListSuite) TestDiffCompactsAtEnd(c *C) {
+	forEachRefList(func(f reflistFactory) {
+		db, _ := goleveldb.NewOpenDB(c.MkDir())
+		coll := NewPackageCollection(db)
 
-	listA := NewPackageList()
-	listA.Add(packages[0])
-	listA.Add(packages[1])
-	listA.Add(packages[2])
-	listA.Add(packages[3])
-	listA.Add(packages[6])
+		packages := []*Package{
+			{Name: "app", Version: "1.1~bp1", Architecture: "i386"},  //0
+			{Name: "app", Version: "1.1~bp2", Architecture: "i386"},  //1
+			{Name: "app", Version: "1.1~bp2", Architecture: "amd64"}, //2
+		}
 
-	listB := NewPackageList()
-	listB.Add(packages[0])
-	listB.Add(packages[2])
-	listB.Add(packages[4])
-	listB.Add(packages[5])
+		for _, p := range packages {
+			coll.Update(p)
+		}
 
-	reflistA := NewPackageRefListFromPackageList(listA)
-	reflistB := NewPackageRefListFromPackageList(listB)
+		listA := NewPackageList()
+		listA.Add(packages[0])
 
-	diffAA, err := reflistA.Diff(reflistA, coll)
-	c.Check(err, IsNil)
-	c.Check(diffAA, HasLen, 0)
+		listB := NewPackageList()
+		listB.Add(packages[1])
+		listB.Add(packages[2])
 
-	diffAB, err := reflistA.Diff(reflistB, coll)
-	c.Check(err, IsNil)
-	c.Check(diffAB, HasLen, 4)
+		reflistA := f.newFromPackageList(listA)
+		reflistB := f.newFromPackageList(listB)
 
-	c.Check(diffAB[0].Left, IsNil)
-	c.Check(diffAB[0].Right.String(), Equals, "app_1.1~bp2_amd64")
+		diffAB, err := diffRefLists(reflistA, reflistB, coll)
+		c.Check(err, IsNil)
+		c.Check(diffAB, HasLen, 2)
+
+		c.Check(diffAB[0].Left, IsNil)
+		c.Check(diffAB[0].Right.String(), Equals, "app_1.1~bp2_amd64")
+
+		c.Check(diffAB[1].Left.String(), Equals, "app_1.1~bp1_i386")
+		c.Check(diffAB[1].Right.String(), Equals, "app_1.1~bp2_i386")
+	})
+}
 
-	c.Check(diffAB[1].Left.String(), Equals, "app_1.1~bp1_i386")
-	c.Check(diffAB[1].Right.String(), Equals, "app_1.1~bp2_i386")
+func mergeRefLists(l, r AnyRefList, overrideMatching, ignoreConflicting bool) AnyRefList {
+	switch l := l.(type) {
+	case *PackageRefList:
+		return l.Merge(r.(*PackageRefList), overrideMatching, ignoreConflicting)
+	case *SplitRefList:
+		return l.Merge(r.(*SplitRefList), overrideMatching, ignoreConflicting)
+	default:
+		panic(fmt.Sprintf("unexpected reflist type %t", l))
+	}
+}
 
-	c.Check(diffAB[2].Left.String(), Equals, "dpkg_1.7_i386")
-	c.Check(diffAB[2].Right, IsNil)
+func (s *PackageRefListSuite) TestMerge(c *C) {
+	forEachRefList(func(f reflistFactory) {
+		db, _ := goleveldb.NewOpenDB(c.MkDir())
+		coll := NewPackageCollection(db)
+
+		packages := []*Package{
+			{Name: "lib", Version: "1.0", Architecture: "i386"},                      //0
+			{Name: "dpkg", Version: "1.7", Architecture: "i386"},                     //1
+			{Name: "data", Version: "1.1~bp1", Architecture: "all"},                  //2
+			{Name: "app", Version: "1.1~bp1", Architecture: "i386"},                  //3
+			{Name: "app", Version: "1.1~bp2", Architecture: "i386"},                  //4
+			{Name: "app", Version: "1.1~bp2", Architecture: "amd64"},                 //5
+			{Name: "dpkg", Version: "1.0", Architecture: "i386"},                     //6
+			{Name: "xyz", Version: "1.0", Architecture: "sparc"},                     //7
+			{Name: "dpkg", Version: "1.0", Architecture: "i386", FilesHash: 0x34445}, //8
+			{Name: "app", Version: "1.1~bp2", Architecture: "i386", FilesHash: 0x44}, //9
+		}
+
+		for _, p := range packages {
+			p.V06Plus = true
+			coll.Update(p)
+		}
+
+		listA := NewPackageList()
+		listA.Add(packages[0])
+		listA.Add(packages[1])
+		listA.Add(packages[2])
+		listA.Add(packages[3])
+		listA.Add(packages[7])
+
+		listB := NewPackageList()
+		listB.Add(packages[0])
+		listB.Add(packages[2])
+		listB.Add(packages[4])
+		listB.Add(packages[5])
+		listB.Add(packages[6])
+
+		listC := NewPackageList()
+		listC.Add(packages[0])
+		listC.Add(packages[8])
+		listC.Add(packages[9])
+
+		reflistA := f.newFromPackageList(listA)
+		reflistB := f.newFromPackageList(listB)
+		reflistC := f.newFromPackageList(listC)
+
+		mergeAB := mergeRefLists(reflistA, reflistB, true, false)
+		mergeBA := mergeRefLists(reflistB, reflistA, true, false)
+		mergeAC := mergeRefLists(reflistA, reflistC, true, false)
+		mergeBC := mergeRefLists(reflistB, reflistC, true, false)
+		mergeCB := mergeRefLists(reflistC, reflistB, true, false)
+
+		verifyRefListIntegrity(c, mergeAB)
+		verifyRefListIntegrity(c, mergeBA)
+		verifyRefListIntegrity(c, mergeAC)
+		verifyRefListIntegrity(c, mergeBC)
+		verifyRefListIntegrity(c, mergeCB)
+
+		c.Check(toStrSlice(mergeAB), DeepEquals,
+			[]string{"Pall data 1.1~bp1 00000000", "Pamd64 app 1.1~bp2 00000000", "Pi386 app 1.1~bp2 00000000", "Pi386 dpkg 1.0 00000000", "Pi386 lib 1.0 00000000", "Psparc xyz 1.0 00000000"})
+		c.Check(toStrSlice(mergeBA), DeepEquals,
+			[]string{"Pall data 1.1~bp1 00000000", "Pamd64 app 1.1~bp2 00000000", "Pi386 app 1.1~bp1 00000000", "Pi386 dpkg 1.7 00000000", "Pi386 lib 1.0 00000000", "Psparc xyz 1.0 00000000"})
+		c.Check(toStrSlice(mergeAC), DeepEquals,
+			[]string{"Pall data 1.1~bp1 00000000", "Pi386 app 1.1~bp2 00000044", "Pi386 dpkg 1.0 00034445", "Pi386 lib 1.0 00000000", "Psparc xyz 1.0 00000000"})
+		c.Check(toStrSlice(mergeBC), DeepEquals,
+			[]string{"Pall data 1.1~bp1 00000000", "Pamd64 app 1.1~bp2 00000000", "Pi386 app 1.1~bp2 00000044", "Pi386 dpkg 1.0 00034445", "Pi386 lib 1.0 00000000"})
+		c.Check(toStrSlice(mergeCB), DeepEquals,
+			[]string{"Pall data 1.1~bp1 00000000", "Pamd64 app 1.1~bp2 00000000", "Pi386 app 1.1~bp2 00000000", "Pi386 dpkg 1.0 00000000", "Pi386 lib 1.0 00000000"})
+
+		mergeABall := mergeRefLists(reflistA, reflistB, false, false)
+		mergeBAall := mergeRefLists(reflistB, reflistA, false, false)
+		mergeACall := mergeRefLists(reflistA, reflistC, false, false)
+		mergeBCall := mergeRefLists(reflistB, reflistC, false, false)
+		mergeCBall := mergeRefLists(reflistC, reflistB, false, false)
+
+		verifyRefListIntegrity(c, mergeABall)
+		verifyRefListIntegrity(c, mergeBAall)
+		verifyRefListIntegrity(c, mergeACall)
+		verifyRefListIntegrity(c, mergeBCall)
+		verifyRefListIntegrity(c, mergeCBall)
+
+		c.Check(mergeABall, DeepEquals, mergeBAall)
+		c.Check(toStrSlice(mergeBAall), DeepEquals,
+			[]string{"Pall data 1.1~bp1 00000000", "Pamd64 app 1.1~bp2 00000000", "Pi386 app 1.1~bp1 00000000", "Pi386 app 1.1~bp2 00000000",
+				"Pi386 dpkg 1.0 00000000", "Pi386 dpkg 1.7 00000000", "Pi386 lib 1.0 00000000", "Psparc xyz 1.0 00000000"})
+
+		c.Check(mergeBCall, Not(DeepEquals), mergeCBall)
+		c.Check(toStrSlice(mergeACall), DeepEquals,
+			[]string{"Pall data 1.1~bp1 00000000", "Pi386 app 1.1~bp1 00000000", "Pi386 app 1.1~bp2 00000044", "Pi386 dpkg 1.0 00034445",
+				"Pi386 dpkg 1.7 00000000", "Pi386 lib 1.0 00000000", "Psparc xyz 1.0 00000000"})
+		c.Check(toStrSlice(mergeBCall), DeepEquals,
+			[]string{"Pall data 1.1~bp1 00000000", "Pamd64 app 1.1~bp2 00000000", "Pi386 app 1.1~bp2 00000044", "Pi386 dpkg 1.0 00034445",
+				"Pi386 lib 1.0 00000000"})
+
+		mergeBCwithConflicts := mergeRefLists(reflistB, reflistC, false, true)
+		c.Check(toStrSlice(mergeBCwithConflicts), DeepEquals,
+			[]string{"Pall data 1.1~bp1 00000000", "Pamd64 app 1.1~bp2 00000000", "Pi386 app 1.1~bp2 00000000", "Pi386 app 1.1~bp2 00000044",
+				"Pi386 dpkg 1.0 00000000", "Pi386 dpkg 1.0 00034445", "Pi386 lib 1.0 00000000"})
+	})
+}
 
-	c.Check(diffAB[3].Left.String(), Equals, "xyz_3.0_sparc")
-	c.Check(diffAB[3].Right, IsNil)
+func (s *PackageRefListSuite) TestFilterLatestRefs(c *C) {
+	forEachRefList(func(f reflistFactory) {
+		packages := []*Package{
+			{Name: "lib", Version: "1.0", Architecture: "i386"},
+			{Name: "lib", Version: "1.2~bp1", Architecture: "i386"},
+			{Name: "lib", Version: "1.2", Architecture: "i386"},
+			{Name: "dpkg", Version: "1.2", Architecture: "i386"},
+			{Name: "dpkg", Version: "1.3", Architecture: "i386"},
+			{Name: "dpkg", Version: "1.3~bp2", Architecture: "i386"},
+			{Name: "dpkg", Version: "1.5", Architecture: "i386"},
+			{Name: "dpkg", Version: "1.6", Architecture: "i386"},
+		}
+
+		rl := NewPackageList()
+		rl.Add(packages[0])
+		rl.Add(packages[1])
+		rl.Add(packages[2])
+		rl.Add(packages[3])
+		rl.Add(packages[4])
+		rl.Add(packages[5])
+		rl.Add(packages[6])
+		rl.Add(packages[7])
+
+		result := f.newFromPackageList(rl)
+		result.FilterLatestRefs()
+
+		verifyRefListIntegrity(c, result)
+		c.Check(toStrSlice(result), DeepEquals,
+			[]string{"Pi386 dpkg 1.6", "Pi386 lib 1.2"})
+	})
+}
 
-	diffBA, err := reflistB.Diff(reflistA, coll)
-	c.Check(err, IsNil)
-	c.Check(diffBA, HasLen, 4)
+func (s *PackageRefListSuite) TestPackageRefListEncodeDecode(c *C) {
+	list := NewPackageList()
+	list.Add(s.p1)
+	list.Add(s.p3)
+	list.Add(s.p5)
+	list.Add(s.p6)
 
-	c.Check(diffBA[0].Right, IsNil)
-	c.Check(diffBA[0].Left.String(), Equals, "app_1.1~bp2_amd64")
+	reflist := NewPackageRefListFromPackageList(list)
 
-	c.Check(diffBA[1].Right.String(), Equals, "app_1.1~bp1_i386")
-	c.Check(diffBA[1].Left.String(), Equals, "app_1.1~bp2_i386")
+	reflist2 := &PackageRefList{}
+	err := reflist2.Decode(reflist.Encode())
+	c.Assert(err, IsNil)
+	c.Check(reflist2.Len(), Equals, reflist.Len())
+	c.Check(reflist2.Refs, DeepEquals, reflist.Refs)
+}
 
-	c.Check(diffBA[2].Right.String(), Equals, "dpkg_1.7_i386")
-	c.Check(diffBA[2].Left, IsNil)
+func (s *PackageRefListSuite) TestRefListBucketPrefix(c *C) {
+	c.Check(bucketRefPrefix([]byte("Pall abcd 1.0")), DeepEquals, []byte("abc"))
+	c.Check(bucketRefPrefix([]byte("Pall libabcd 1.0")), DeepEquals, []byte("abc"))
+	c.Check(bucketRefPrefix([]byte("Pamd64 xy 1.0")), DeepEquals, []byte("xy"))
+}
 
-	c.Check(diffBA[3].Right.String(), Equals, "xyz_3.0_sparc")
-	c.Check(diffBA[3].Left, IsNil)
+func (s *PackageRefListSuite) TestRefListBucketIdx(c *C) {
+	c.Check(bucketIdxForRef(s.p1.Key("")), Equals, 46)
+	c.Check(bucketIdxForRef(s.p2.Key("")), Equals, 46)
+	c.Check(bucketIdxForRef(s.p3.Key("")), Equals, 26)
+	c.Check(bucketIdxForRef(s.p4.Key("")), Equals, 46)
+	c.Check(bucketIdxForRef(s.p5.Key("")), Equals, 4)
+	c.Check(bucketIdxForRef(s.p6.Key("")), Equals, 46)
+}
 
+func (s *PackageRefListSuite) TestSplitRefListBuckets(c *C) {
+	list := NewPackageList()
+	list.Add(s.p1)
+	list.Add(s.p3)
+	list.Add(s.p4)
+	list.Add(s.p5)
+	list.Add(s.p6)
+
+	sl := NewSplitRefListFromPackageList(list)
+	verifyRefListIntegrity(c, sl)
+
+	c.Check(hex.EncodeToString(sl.Buckets[4]), Equals, "7287aed32daad5d1aab4e89533bde135381d932e60548cfc00b882ca8858ae07")
+	c.Check(toStrSlice(sl.bucketRefs[4]), DeepEquals, []string{string(s.p5.Key(""))})
+	c.Check(hex.EncodeToString(sl.Buckets[26]), Equals, "f31fc28e82368b63c8be47eefc64b8e217e2e5349c7e3827b98f80536b956f6e")
+	c.Check(toStrSlice(sl.bucketRefs[26]), DeepEquals, []string{string(s.p3.Key(""))})
+	c.Check(hex.EncodeToString(sl.Buckets[46]), Equals, "55e70286393afc5da5046d68c632d35f98bec24781ae433bd1a1069b52853367")
+	c.Check(toStrSlice(sl.bucketRefs[46]), DeepEquals, []string{string(s.p1.Key("")), string(s.p6.Key(""))})
 }
 
-func (s *PackageRefListSuite) TestDiffCompactsAtEnd(c *C) {
-	db, _ := goleveldb.NewOpenDB(c.MkDir())
-	coll := NewPackageCollection(db)
+func (s *PackageRefListSuite) TestRefListDigestSet(c *C) {
+	list := NewPackageList()
+	list.Add(s.p1)
+	list.Add(s.p3)
+	list.Add(s.p4)
+	list.Add(s.p5)
+	list.Add(s.p6)
 
-	packages := []*Package{
-		{Name: "app", Version: "1.1~bp1", Architecture: "i386"},  //0
-		{Name: "app", Version: "1.1~bp2", Architecture: "i386"},  //1
-		{Name: "app", Version: "1.1~bp2", Architecture: "amd64"}, //2
-	}
+	sl := NewSplitRefListFromPackageList(list)
 
-	for _, p := range packages {
-		coll.Update(p)
-	}
+	set := NewRefListDigestSet()
+	c.Check(set.Len(), Equals, 0)
 
-	listA := NewPackageList()
-	listA.Add(packages[0])
+	err := sl.ForEachBucket(func(digest []byte, bucket *PackageRefList) error {
+		c.Check(set.Has(digest), Equals, false)
+		return nil
+	})
+	c.Assert(err, IsNil)
 
-	listB := NewPackageList()
-	listB.Add(packages[1])
-	listB.Add(packages[2])
+	set.AddAllInRefList(sl)
+	c.Check(set.Len(), Equals, 3)
 
-	reflistA := NewPackageRefListFromPackageList(listA)
-	reflistB := NewPackageRefListFromPackageList(listB)
+	err = sl.ForEachBucket(func(digest []byte, bucket *PackageRefList) error {
+		c.Check(set.Has(digest), Equals, true)
+		return nil
+	})
+	c.Assert(err, IsNil)
 
-	diffAB, err := reflistA.Diff(reflistB, coll)
-	c.Check(err, IsNil)
-	c.Check(diffAB, HasLen, 2)
+	firstDigest := sl.Buckets[bucketIdxForRef(s.p1.Key(""))]
+	set.Remove(firstDigest)
+	c.Check(set.Len(), Equals, 2)
 
-	c.Check(diffAB[0].Left, IsNil)
-	c.Check(diffAB[0].Right.String(), Equals, "app_1.1~bp2_amd64")
+	err = sl.ForEachBucket(func(digest []byte, bucket *PackageRefList) error {
+		c.Check(set.Has(digest), Equals, !bytes.Equal(digest, firstDigest))
+		return nil
+	})
+	c.Assert(err, IsNil)
 
-	c.Check(diffAB[1].Left.String(), Equals, "app_1.1~bp1_i386")
-	c.Check(diffAB[1].Right.String(), Equals, "app_1.1~bp2_i386")
+	set2 := NewRefListDigestSet()
+	set2.AddAllInRefList(sl)
+	set2.RemoveAll(set)
+
+	err = sl.ForEachBucket(func(digest []byte, bucket *PackageRefList) error {
+		c.Check(set2.Has(digest), Equals, bytes.Equal(digest, firstDigest))
+		return nil
+	})
+	c.Assert(err, IsNil)
 }
 
-func (s *PackageRefListSuite) TestMerge(c *C) {
+func (s *PackageRefListSuite) TestRefListCollectionLoadSave(c *C) {
 	db, _ := goleveldb.NewOpenDB(c.MkDir())
-	coll := NewPackageCollection(db)
-
-	packages := []*Package{
-		{Name: "lib", Version: "1.0", Architecture: "i386"},                      //0
-		{Name: "dpkg", Version: "1.7", Architecture: "i386"},                     //1
-		{Name: "data", Version: "1.1~bp1", Architecture: "all"},                  //2
-		{Name: "app", Version: "1.1~bp1", Architecture: "i386"},                  //3
-		{Name: "app", Version: "1.1~bp2", Architecture: "i386"},                  //4
-		{Name: "app", Version: "1.1~bp2", Architecture: "amd64"},                 //5
-		{Name: "dpkg", Version: "1.0", Architecture: "i386"},                     //6
-		{Name: "xyz", Version: "1.0", Architecture: "sparc"},                     //7
-		{Name: "dpkg", Version: "1.0", Architecture: "i386", FilesHash: 0x34445}, //8
-		{Name: "app", Version: "1.1~bp2", Architecture: "i386", FilesHash: 0x44}, //9
-	}
+	reflistCollection := NewRefListCollection(db)
+	packageCollection := NewPackageCollection(db)
+
+	packageCollection.Update(s.p1)
+	packageCollection.Update(s.p2)
+	packageCollection.Update(s.p3)
+	packageCollection.Update(s.p4)
+	packageCollection.Update(s.p5)
+	packageCollection.Update(s.p6)
+
+	list := NewPackageList()
+	list.Add(s.p1)
+	list.Add(s.p2)
+	list.Add(s.p3)
+	list.Add(s.p4)
+	list.Add(s.p5)
+
+	key := []byte("test")
+
+	reflist := NewPackageRefListFromPackageList(list)
+	db.Put(key, reflist.Encode())
+
+	sl := NewSplitRefList()
+	err := reflistCollection.LoadComplete(sl, key)
+	c.Assert(err, IsNil)
+	verifyRefListIntegrity(c, sl)
+	c.Check(toStrSlice(sl), DeepEquals, toStrSlice(reflist))
 
-	for _, p := range packages {
-		p.V06Plus = true
-		coll.Update(p)
-	}
+	list.Add(s.p6)
+	sl = NewSplitRefListFromPackageList(list)
+	err = reflistCollection.Update(sl, key)
+	c.Assert(err, IsNil)
 
-	listA := NewPackageList()
-	listA.Add(packages[0])
-	listA.Add(packages[1])
-	listA.Add(packages[2])
-	listA.Add(packages[3])
-	listA.Add(packages[7])
-
-	listB := NewPackageList()
-	listB.Add(packages[0])
-	listB.Add(packages[2])
-	listB.Add(packages[4])
-	listB.Add(packages[5])
-	listB.Add(packages[6])
-
-	listC := NewPackageList()
-	listC.Add(packages[0])
-	listC.Add(packages[8])
-	listC.Add(packages[9])
-
-	reflistA := NewPackageRefListFromPackageList(listA)
-	reflistB := NewPackageRefListFromPackageList(listB)
-	reflistC := NewPackageRefListFromPackageList(listC)
-
-	mergeAB := reflistA.Merge(reflistB, true, false)
-	mergeBA := reflistB.Merge(reflistA, true, false)
-	mergeAC := reflistA.Merge(reflistC, true, false)
-	mergeBC := reflistB.Merge(reflistC, true, false)
-	mergeCB := reflistC.Merge(reflistB, true, false)
-
-	c.Check(toStrSlice(mergeAB), DeepEquals,
-		[]string{"Pall data 1.1~bp1 00000000", "Pamd64 app 1.1~bp2 00000000", "Pi386 app 1.1~bp2 00000000", "Pi386 dpkg 1.0 00000000", "Pi386 lib 1.0 00000000", "Psparc xyz 1.0 00000000"})
-	c.Check(toStrSlice(mergeBA), DeepEquals,
-		[]string{"Pall data 1.1~bp1 00000000", "Pamd64 app 1.1~bp2 00000000", "Pi386 app 1.1~bp1 00000000", "Pi386 dpkg 1.7 00000000", "Pi386 lib 1.0 00000000", "Psparc xyz 1.0 00000000"})
-	c.Check(toStrSlice(mergeAC), DeepEquals,
-		[]string{"Pall data 1.1~bp1 00000000", "Pi386 app 1.1~bp2 00000044", "Pi386 dpkg 1.0 00034445", "Pi386 lib 1.0 00000000", "Psparc xyz 1.0 00000000"})
-	c.Check(toStrSlice(mergeBC), DeepEquals,
-		[]string{"Pall data 1.1~bp1 00000000", "Pamd64 app 1.1~bp2 00000000", "Pi386 app 1.1~bp2 00000044", "Pi386 dpkg 1.0 00034445", "Pi386 lib 1.0 00000000"})
-	c.Check(toStrSlice(mergeCB), DeepEquals,
-		[]string{"Pall data 1.1~bp1 00000000", "Pamd64 app 1.1~bp2 00000000", "Pi386 app 1.1~bp2 00000000", "Pi386 dpkg 1.0 00000000", "Pi386 lib 1.0 00000000"})
-
-	mergeABall := reflistA.Merge(reflistB, false, false)
-	mergeBAall := reflistB.Merge(reflistA, false, false)
-	mergeACall := reflistA.Merge(reflistC, false, false)
-	mergeBCall := reflistB.Merge(reflistC, false, false)
-	mergeCBall := reflistC.Merge(reflistB, false, false)
-
-	c.Check(mergeABall, DeepEquals, mergeBAall)
-	c.Check(toStrSlice(mergeBAall), DeepEquals,
-		[]string{"Pall data 1.1~bp1 00000000", "Pamd64 app 1.1~bp2 00000000", "Pi386 app 1.1~bp1 00000000", "Pi386 app 1.1~bp2 00000000",
-			"Pi386 dpkg 1.0 00000000", "Pi386 dpkg 1.7 00000000", "Pi386 lib 1.0 00000000", "Psparc xyz 1.0 00000000"})
-
-	c.Check(mergeBCall, Not(DeepEquals), mergeCBall)
-	c.Check(toStrSlice(mergeACall), DeepEquals,
-		[]string{"Pall data 1.1~bp1 00000000", "Pi386 app 1.1~bp1 00000000", "Pi386 app 1.1~bp2 00000044", "Pi386 dpkg 1.0 00034445",
-			"Pi386 dpkg 1.7 00000000", "Pi386 lib 1.0 00000000", "Psparc xyz 1.0 00000000"})
-	c.Check(toStrSlice(mergeBCall), DeepEquals,
-		[]string{"Pall data 1.1~bp1 00000000", "Pamd64 app 1.1~bp2 00000000", "Pi386 app 1.1~bp2 00000044", "Pi386 dpkg 1.0 00034445",
-			"Pi386 lib 1.0 00000000"})
-
-	mergeBCwithConflicts := reflistB.Merge(reflistC, false, true)
-	c.Check(toStrSlice(mergeBCwithConflicts), DeepEquals,
-		[]string{"Pall data 1.1~bp1 00000000", "Pamd64 app 1.1~bp2 00000000", "Pi386 app 1.1~bp2 00000000", "Pi386 app 1.1~bp2 00000044",
-			"Pi386 dpkg 1.0 00000000", "Pi386 dpkg 1.0 00034445", "Pi386 lib 1.0 00000000"})
+	sl = NewSplitRefList()
+	err = reflistCollection.LoadComplete(sl, key)
+	c.Assert(err, IsNil)
+	verifyRefListIntegrity(c, sl)
+	c.Check(toStrSlice(sl), DeepEquals, toStrSlice(NewPackageRefListFromPackageList(list)))
 }
 
-func (s *PackageRefListSuite) TestFilterLatestRefs(c *C) {
-	packages := []*Package{
-		{Name: "lib", Version: "1.0", Architecture: "i386"},
-		{Name: "lib", Version: "1.2~bp1", Architecture: "i386"},
-		{Name: "lib", Version: "1.2", Architecture: "i386"},
-		{Name: "dpkg", Version: "1.2", Architecture: "i386"},
-		{Name: "dpkg", Version: "1.3", Architecture: "i386"},
-		{Name: "dpkg", Version: "1.3~bp2", Architecture: "i386"},
-		{Name: "dpkg", Version: "1.5", Architecture: "i386"},
-		{Name: "dpkg", Version: "1.6", Architecture: "i386"},
-	}
+func (s *PackageRefListSuite) TestRefListCollectionMigrate(c *C) {
+	db, _ := goleveldb.NewOpenDB(c.MkDir())
+	reflistCollection := NewRefListCollection(db)
+	packageCollection := NewPackageCollection(db)
+
+	packageCollection.Update(s.p1)
+	packageCollection.Update(s.p2)
+	packageCollection.Update(s.p3)
+	packageCollection.Update(s.p4)
+	packageCollection.Update(s.p5)
+	packageCollection.Update(s.p6)
+
+	list := NewPackageList()
+	list.Add(s.p1)
+	list.Add(s.p2)
+	list.Add(s.p3)
+	list.Add(s.p4)
+	list.Add(s.p5)
+
+	key := []byte("test")
+
+	reflist := NewPackageRefListFromPackageList(list)
+	db.Put(key, reflist.Encode())
+
+	sl := NewSplitRefList()
+	format, err := reflistCollection.load(sl, key)
+	c.Assert(err, IsNil)
+	c.Check(format, Equals, reflistStorageFormatInline)
+
+	migrator := reflistCollection.NewMigration()
+	err = reflistCollection.LoadCompleteAndMigrate(sl, key, migrator)
+	c.Assert(err, IsNil)
+	verifyRefListIntegrity(c, sl)
+	c.Check(toStrSlice(sl), DeepEquals, toStrSlice(NewPackageRefListFromPackageList(list)))
 
-	rl := NewPackageList()
-	rl.Add(packages[0])
-	rl.Add(packages[1])
-	rl.Add(packages[2])
-	rl.Add(packages[3])
-	rl.Add(packages[4])
-	rl.Add(packages[5])
-	rl.Add(packages[6])
-	rl.Add(packages[7])
-
-	result := NewPackageRefListFromPackageList(rl)
-	result.FilterLatestRefs()
-
-	c.Check(toStrSlice(result), DeepEquals,
-		[]string{"Pi386 dpkg 1.6", "Pi386 lib 1.2"})
+	stats := migrator.Stats()
+	c.Check(stats.Reflists, Equals, 0)
+	c.Check(stats.Buckets, Equals, 0)
+	c.Check(stats.Segments, Equals, 0)
+
+	err = migrator.Flush()
+	c.Assert(err, IsNil)
+	stats = migrator.Stats()
+	c.Check(stats.Reflists, Equals, 1)
+	c.Check(stats.Buckets, Not(Equals), 0)
+	c.Check(stats.Segments, Equals, stats.Segments)
+
+	sl = NewSplitRefList()
+	err = reflistCollection.LoadComplete(sl, key)
+	c.Assert(err, IsNil)
+	verifyRefListIntegrity(c, sl)
+	c.Check(toStrSlice(sl), DeepEquals, toStrSlice(NewPackageRefListFromPackageList(list)))
+
+	format, err = reflistCollection.load(sl, key)
+	c.Assert(err, IsNil)
+	c.Check(format, Equals, reflistStorageFormatSplit)
 }
diff --git a/deb/remote.go b/deb/remote.go
index f94dffaf9..57cf3c6e9 100644
--- a/deb/remote.go
+++ b/deb/remote.go
@@ -73,7 +73,7 @@ type RemoteRepo struct {
 	// Packages for json output
 	Packages []string `codec:"-" json:",omitempty"`
 	// "Snapshot" of current list of packages
-	packageRefs *PackageRefList
+	packageRefs *SplitRefList
 	// Parsed archived root
 	archiveRootURL *url.URL
 	// Current list of packages (filled while updating mirror)
@@ -171,7 +171,7 @@ func (repo *RemoteRepo) NumPackages() int {
 }
 
 // RefList returns package list for repo
-func (repo *RemoteRepo) RefList() *PackageRefList {
+func (repo *RemoteRepo) RefList() *SplitRefList {
 	return repo.packageRefs
 }
 
@@ -662,7 +662,7 @@ func (repo *RemoteRepo) FinalizeDownload(collectionFactory *CollectionFactory, p
 	})
 
 	if err == nil {
-		repo.packageRefs = NewPackageRefListFromPackageList(repo.packageList)
+		repo.packageRefs = NewSplitRefListFromPackageList(repo.packageList)
 		repo.packageList = nil
 	}
 
@@ -804,14 +804,14 @@ func (collection *RemoteRepoCollection) search(filter func(*RemoteRepo) bool, un
 }
 
 // Add appends new repo to collection and saves it
-func (collection *RemoteRepoCollection) Add(repo *RemoteRepo) error {
+func (collection *RemoteRepoCollection) Add(repo *RemoteRepo, reflistCollection *RefListCollection) error {
 	_, err := collection.ByName(repo.Name)
 
 	if err == nil {
 		return fmt.Errorf("mirror with name %s already exists", repo.Name)
 	}
 
-	err = collection.Update(repo)
+	err = collection.Update(repo, reflistCollection)
 	if err != nil {
 		return err
 	}
@@ -821,28 +821,26 @@ func (collection *RemoteRepoCollection) Add(repo *RemoteRepo) error {
 }
 
 // Update stores updated information about repo in DB
-func (collection *RemoteRepoCollection) Update(repo *RemoteRepo) error {
+func (collection *RemoteRepoCollection) Update(repo *RemoteRepo, reflistCollection *RefListCollection) error {
 	batch := collection.db.CreateBatch()
 
 	batch.Put(repo.Key(), repo.Encode())
 	if repo.packageRefs != nil {
-		batch.Put(repo.RefKey(), repo.packageRefs.Encode())
+		rb := reflistCollection.NewBatch(batch)
+		reflistCollection.UpdateInBatch(repo.packageRefs, repo.RefKey(), rb)
 	}
 	return batch.Write()
 }
 
 // LoadComplete loads additional information for remote repo
-func (collection *RemoteRepoCollection) LoadComplete(repo *RemoteRepo) error {
-	encoded, err := collection.db.Get(repo.RefKey())
+func (collection *RemoteRepoCollection) LoadComplete(repo *RemoteRepo, reflistCollection *RefListCollection) error {
+	repo.packageRefs = NewSplitRefList()
+	err := reflistCollection.LoadComplete(repo.packageRefs, repo.RefKey())
 	if err == database.ErrNotFound {
 		return nil
 	}
-	if err != nil {
-		return err
-	}
 
-	repo.packageRefs = &PackageRefList{}
-	return repo.packageRefs.Decode(encoded)
+	return err
 }
 
 // ByName looks up repository by name
diff --git a/deb/remote_test.go b/deb/remote_test.go
index c331579f5..3e05ef7e5 100644
--- a/deb/remote_test.go
+++ b/deb/remote_test.go
@@ -52,7 +52,7 @@ func (n *NullVerifier) IsClearSigned(clearsign io.Reader) (bool, error) {
 type PackageListMixinSuite struct {
 	p1, p2, p3 *Package
 	list       *PackageList
-	reflist    *PackageRefList
+	reflist    *SplitRefList
 }
 
 func (s *PackageListMixinSuite) SetUpPackages() {
@@ -72,7 +72,7 @@ func (s *PackageListMixinSuite) SetUpPackages() {
 	s.list.Add(s.p2)
 	s.list.Add(s.p3)
 
-	s.reflist = NewPackageRefListFromPackageList(s.list)
+	s.reflist = NewSplitRefListFromPackageList(s.list)
 }
 
 type RemoteRepoSuite struct {
@@ -291,7 +291,7 @@ func (s *RemoteRepoSuite) TestDownload(c *C) {
 	s.repo.FinalizeDownload(s.collectionFactory, nil)
 	c.Assert(s.repo.packageRefs, NotNil)
 
-	pkg, err := s.collectionFactory.PackageCollection().ByKey(s.repo.packageRefs.Refs[0])
+	pkg, err := s.collectionFactory.PackageCollection().ByKey(s.repo.packageRefs.Flatten().Refs[0])
 	c.Assert(err, IsNil)
 
 	c.Check(pkg.Name, Equals, "amanda-client")
@@ -373,12 +373,12 @@ func (s *RemoteRepoSuite) TestDownloadWithInstaller(c *C) {
 	s.repo.FinalizeDownload(s.collectionFactory, nil)
 	c.Assert(s.repo.packageRefs, NotNil)
 
-	pkg, err := s.collectionFactory.PackageCollection().ByKey(s.repo.packageRefs.Refs[0])
+	pkg, err := s.collectionFactory.PackageCollection().ByKey(s.repo.packageRefs.Flatten().Refs[0])
 	c.Assert(err, IsNil)
 
 	c.Check(pkg.Name, Equals, "amanda-client")
 
-	pkg, err = s.collectionFactory.PackageCollection().ByKey(s.repo.packageRefs.Refs[1])
+	pkg, err = s.collectionFactory.PackageCollection().ByKey(s.repo.packageRefs.Flatten().Refs[1])
 	c.Assert(err, IsNil)
 	c.Check(pkg.Name, Equals, "installer")
 }
@@ -419,12 +419,12 @@ func (s *RemoteRepoSuite) TestDownloadWithSources(c *C) {
 	s.repo.FinalizeDownload(s.collectionFactory, nil)
 	c.Assert(s.repo.packageRefs, NotNil)
 
-	pkg, err := s.collectionFactory.PackageCollection().ByKey(s.repo.packageRefs.Refs[0])
+	pkg, err := s.collectionFactory.PackageCollection().ByKey(s.repo.packageRefs.Flatten().Refs[0])
 	c.Assert(err, IsNil)
 
 	c.Check(pkg.Name, Equals, "amanda-client")
 
-	pkg, err = s.collectionFactory.PackageCollection().ByKey(s.repo.packageRefs.Refs[1])
+	pkg, err = s.collectionFactory.PackageCollection().ByKey(s.repo.packageRefs.Flatten().Refs[1])
 	c.Assert(err, IsNil)
 	c.Check(pkg.Name, Equals, "access-modifier-checker")
 
@@ -503,7 +503,7 @@ func (s *RemoteRepoSuite) TestDownloadFlat(c *C) {
 	s.flat.FinalizeDownload(s.collectionFactory, nil)
 	c.Assert(s.flat.packageRefs, NotNil)
 
-	pkg, err := s.collectionFactory.PackageCollection().ByKey(s.flat.packageRefs.Refs[0])
+	pkg, err := s.collectionFactory.PackageCollection().ByKey(s.flat.packageRefs.Flatten().Refs[0])
 	c.Assert(err, IsNil)
 
 	c.Check(pkg.Name, Equals, "amanda-client")
@@ -593,12 +593,12 @@ func (s *RemoteRepoSuite) TestDownloadWithSourcesFlat(c *C) {
 	s.flat.FinalizeDownload(s.collectionFactory, nil)
 	c.Assert(s.flat.packageRefs, NotNil)
 
-	pkg, err := s.collectionFactory.PackageCollection().ByKey(s.flat.packageRefs.Refs[0])
+	pkg, err := s.collectionFactory.PackageCollection().ByKey(s.flat.packageRefs.Flatten().Refs[0])
 	c.Assert(err, IsNil)
 
 	c.Check(pkg.Name, Equals, "amanda-client")
 
-	pkg, err = s.collectionFactory.PackageCollection().ByKey(s.flat.packageRefs.Refs[1])
+	pkg, err = s.collectionFactory.PackageCollection().ByKey(s.flat.packageRefs.Flatten().Refs[1])
 	c.Assert(err, IsNil)
 
 	c.Check(pkg.Name, Equals, "access-modifier-checker")
@@ -658,8 +658,9 @@ func (s *RemoteRepoSuite) TestDownloadWithSourcesFlat(c *C) {
 
 type RemoteRepoCollectionSuite struct {
 	PackageListMixinSuite
-	db         database.Storage
-	collection *RemoteRepoCollection
+	db                database.Storage
+	collection        *RemoteRepoCollection
+	refListCollection *RefListCollection
 }
 
 var _ = Suite(&RemoteRepoCollectionSuite{})
@@ -667,6 +668,7 @@ var _ = Suite(&RemoteRepoCollectionSuite{})
 func (s *RemoteRepoCollectionSuite) SetUpTest(c *C) {
 	s.db, _ = goleveldb.NewOpenDB(c.MkDir())
 	s.collection = NewRemoteRepoCollection(s.db)
+	s.refListCollection = NewRefListCollection(s.db)
 	s.SetUpPackages()
 }
 
@@ -679,8 +681,8 @@ func (s *RemoteRepoCollectionSuite) TestAddByName(c *C) {
 	c.Assert(err, ErrorMatches, "*.not found")
 
 	repo, _ := NewRemoteRepo("yandex", "http://mirror.yandex.ru/debian/", "squeeze", []string{"main"}, []string{}, false, false, false)
-	c.Assert(s.collection.Add(repo), IsNil)
-	c.Assert(s.collection.Add(repo), ErrorMatches, ".*already exists")
+	c.Assert(s.collection.Add(repo, s.refListCollection), IsNil)
+	c.Assert(s.collection.Add(repo, s.refListCollection), ErrorMatches, ".*already exists")
 
 	r, err := s.collection.ByName("yandex")
 	c.Assert(err, IsNil)
@@ -697,7 +699,7 @@ func (s *RemoteRepoCollectionSuite) TestByUUID(c *C) {
 	c.Assert(err, ErrorMatches, "*.not found")
 
 	repo, _ := NewRemoteRepo("yandex", "http://mirror.yandex.ru/debian/", "squeeze", []string{"main"}, []string{}, false, false, false)
-	c.Assert(s.collection.Add(repo), IsNil)
+	c.Assert(s.collection.Add(repo, s.refListCollection), IsNil)
 
 	r, err := s.collection.ByUUID(repo.UUID)
 	c.Assert(err, IsNil)
@@ -711,7 +713,7 @@ func (s *RemoteRepoCollectionSuite) TestByUUID(c *C) {
 
 func (s *RemoteRepoCollectionSuite) TestUpdateLoadComplete(c *C) {
 	repo, _ := NewRemoteRepo("yandex", "http://mirror.yandex.ru/debian/", "squeeze", []string{"main"}, []string{}, false, false, false)
-	c.Assert(s.collection.Update(repo), IsNil)
+	c.Assert(s.collection.Update(repo, s.refListCollection), IsNil)
 
 	collection := NewRemoteRepoCollection(s.db)
 	r, err := collection.ByName("yandex")
@@ -719,20 +721,20 @@ func (s *RemoteRepoCollectionSuite) TestUpdateLoadComplete(c *C) {
 	c.Assert(r.packageRefs, IsNil)
 
 	repo.packageRefs = s.reflist
-	c.Assert(s.collection.Update(repo), IsNil)
+	c.Assert(s.collection.Update(repo, s.refListCollection), IsNil)
 
 	collection = NewRemoteRepoCollection(s.db)
 	r, err = collection.ByName("yandex")
 	c.Assert(err, IsNil)
 	c.Assert(r.packageRefs, IsNil)
 	c.Assert(r.NumPackages(), Equals, 0)
-	c.Assert(s.collection.LoadComplete(r), IsNil)
+	c.Assert(s.collection.LoadComplete(r, s.refListCollection), IsNil)
 	c.Assert(r.NumPackages(), Equals, 3)
 }
 
 func (s *RemoteRepoCollectionSuite) TestForEachAndLen(c *C) {
 	repo, _ := NewRemoteRepo("yandex", "http://mirror.yandex.ru/debian/", "squeeze", []string{"main"}, []string{}, false, false, false)
-	s.collection.Add(repo)
+	s.collection.Add(repo, s.refListCollection)
 
 	count := 0
 	err := s.collection.ForEach(func(*RemoteRepo) error {
@@ -754,10 +756,10 @@ func (s *RemoteRepoCollectionSuite) TestForEachAndLen(c *C) {
 
 func (s *RemoteRepoCollectionSuite) TestDrop(c *C) {
 	repo1, _ := NewRemoteRepo("yandex", "http://mirror.yandex.ru/debian/", "squeeze", []string{"main"}, []string{}, false, false, false)
-	s.collection.Add(repo1)
+	s.collection.Add(repo1, s.refListCollection)
 
 	repo2, _ := NewRemoteRepo("tyndex", "http://mirror.yandex.ru/debian/", "wheezy", []string{"main"}, []string{}, false, false, false)
-	s.collection.Add(repo2)
+	s.collection.Add(repo2, s.refListCollection)
 
 	r1, _ := s.collection.ByUUID(repo1.UUID)
 	c.Check(r1, Equals, repo1)
diff --git a/deb/snapshot.go b/deb/snapshot.go
index 0457f25a6..00995e7a1 100644
--- a/deb/snapshot.go
+++ b/deb/snapshot.go
@@ -40,12 +40,12 @@ type Snapshot struct {
 	NotAutomatic         string
 	ButAutomaticUpgrades string
 
-	packageRefs *PackageRefList
+	packageRefs *SplitRefList
 }
 
 // NewSnapshotFromRepository creates snapshot from current state of repository
 func NewSnapshotFromRepository(name string, repo *RemoteRepo) (*Snapshot, error) {
-	if repo.packageRefs == nil {
+	if repo.packageRefs == nil || repo.packageRefs.Len() == 0 {
 		return nil, errors.New("mirror not updated")
 	}
 
@@ -76,7 +76,7 @@ func NewSnapshotFromLocalRepo(name string, repo *LocalRepo) (*Snapshot, error) {
 	}
 
 	if snap.packageRefs == nil {
-		snap.packageRefs = NewPackageRefList()
+		snap.packageRefs = NewSplitRefList()
 	}
 
 	return snap, nil
@@ -84,11 +84,13 @@ func NewSnapshotFromLocalRepo(name string, repo *LocalRepo) (*Snapshot, error) {
 
 // NewSnapshotFromPackageList creates snapshot from PackageList
 func NewSnapshotFromPackageList(name string, sources []*Snapshot, list *PackageList, description string) *Snapshot {
-	return NewSnapshotFromRefList(name, sources, NewPackageRefListFromPackageList(list), description)
+	sl := NewSplitRefList()
+	sl.Replace(NewPackageRefListFromPackageList(list))
+	return NewSnapshotFromRefList(name, sources, sl, description)
 }
 
-// NewSnapshotFromRefList creates snapshot from PackageRefList
-func NewSnapshotFromRefList(name string, sources []*Snapshot, list *PackageRefList, description string) *Snapshot {
+// NewSnapshotFromRefList creates snapshot from SplitRefList
+func NewSnapshotFromRefList(name string, sources []*Snapshot, list *SplitRefList, description string) *Snapshot {
 	sourceUUIDs := make([]string, len(sources))
 	for i := range sources {
 		sourceUUIDs[i] = sources[i].UUID
@@ -112,11 +114,14 @@ func (s *Snapshot) String() string {
 
 // NumPackages returns number of packages in snapshot
 func (s *Snapshot) NumPackages() int {
+	if s.packageRefs == nil {
+		return 0
+	}
 	return s.packageRefs.Len()
 }
 
 // RefList returns list of package refs in snapshot
-func (s *Snapshot) RefList() *PackageRefList {
+func (s *Snapshot) RefList() *SplitRefList {
 	return s.packageRefs
 }
 
@@ -209,13 +214,13 @@ func NewSnapshotCollection(db database.Storage) *SnapshotCollection {
 }
 
 // Add appends new repo to collection and saves it
-func (collection *SnapshotCollection) Add(snapshot *Snapshot) error {
+func (collection *SnapshotCollection) Add(snapshot *Snapshot, reflistCollection *RefListCollection) error {
 	_, err := collection.ByName(snapshot.Name)
 	if err == nil {
 		return fmt.Errorf("snapshot with name %s already exists", snapshot.Name)
 	}
 
-	err = collection.Update(snapshot)
+	err = collection.Update(snapshot, reflistCollection)
 	if err != nil {
 		return err
 	}
@@ -225,26 +230,22 @@ func (collection *SnapshotCollection) Add(snapshot *Snapshot) error {
 }
 
 // Update stores updated information about snapshot in DB
-func (collection *SnapshotCollection) Update(snapshot *Snapshot) error {
+func (collection *SnapshotCollection) Update(snapshot *Snapshot, reflistCollection *RefListCollection) error {
 	batch := collection.db.CreateBatch()
 
 	batch.Put(snapshot.Key(), snapshot.Encode())
 	if snapshot.packageRefs != nil {
-		batch.Put(snapshot.RefKey(), snapshot.packageRefs.Encode())
+		rb := reflistCollection.NewBatch(batch)
+		reflistCollection.UpdateInBatch(snapshot.packageRefs, snapshot.RefKey(), rb)
 	}
 
 	return batch.Write()
 }
 
 // LoadComplete loads additional information about snapshot
-func (collection *SnapshotCollection) LoadComplete(snapshot *Snapshot) error {
-	encoded, err := collection.db.Get(snapshot.RefKey())
-	if err != nil {
-		return err
-	}
-
-	snapshot.packageRefs = &PackageRefList{}
-	return snapshot.packageRefs.Decode(encoded)
+func (collection *SnapshotCollection) LoadComplete(snapshot *Snapshot, reflistCollection *RefListCollection) error {
+	snapshot.packageRefs = NewSplitRefList()
+	return reflistCollection.LoadComplete(snapshot.packageRefs, snapshot.RefKey())
 }
 
 func (collection *SnapshotCollection) search(filter func(*Snapshot) bool, unique bool) []*Snapshot {
diff --git a/deb/snapshot_bench_test.go b/deb/snapshot_bench_test.go
index c6bb94a2c..4475ca57b 100644
--- a/deb/snapshot_bench_test.go
+++ b/deb/snapshot_bench_test.go
@@ -18,10 +18,11 @@ func BenchmarkSnapshotCollectionForEach(b *testing.B) {
 	defer db.Close()
 
 	collection := NewSnapshotCollection(db)
+	reflistCollection := NewRefListCollection(db)
 
 	for i := 0; i < count; i++ {
-		snapshot := NewSnapshotFromRefList(fmt.Sprintf("snapshot%d", i), nil, NewPackageRefList(), fmt.Sprintf("Snapshot number %d", i))
-		if collection.Add(snapshot) != nil {
+		snapshot := NewSnapshotFromRefList(fmt.Sprintf("snapshot%d", i), nil, NewSplitRefList(), fmt.Sprintf("Snapshot number %d", i))
+		if collection.Add(snapshot, reflistCollection) != nil {
 			b.FailNow()
 		}
 	}
@@ -47,11 +48,12 @@ func BenchmarkSnapshotCollectionByUUID(b *testing.B) {
 	defer db.Close()
 
 	collection := NewSnapshotCollection(db)
+	reflistCollection := NewRefListCollection(db)
 
 	uuids := []string{}
 	for i := 0; i < count; i++ {
-		snapshot := NewSnapshotFromRefList(fmt.Sprintf("snapshot%d", i), nil, NewPackageRefList(), fmt.Sprintf("Snapshot number %d", i))
-		if collection.Add(snapshot) != nil {
+		snapshot := NewSnapshotFromRefList(fmt.Sprintf("snapshot%d", i), nil, NewSplitRefList(), fmt.Sprintf("Snapshot number %d", i))
+		if collection.Add(snapshot, reflistCollection) != nil {
 			b.FailNow()
 		}
 		uuids = append(uuids, snapshot.UUID)
@@ -78,10 +80,11 @@ func BenchmarkSnapshotCollectionByName(b *testing.B) {
 	defer db.Close()
 
 	collection := NewSnapshotCollection(db)
+	reflistCollection := NewRefListCollection(db)
 
 	for i := 0; i < count; i++ {
-		snapshot := NewSnapshotFromRefList(fmt.Sprintf("snapshot%d", i), nil, NewPackageRefList(), fmt.Sprintf("Snapshot number %d", i))
-		if collection.Add(snapshot) != nil {
+		snapshot := NewSnapshotFromRefList(fmt.Sprintf("snapshot%d", i), nil, NewSplitRefList(), fmt.Sprintf("Snapshot number %d", i))
+		if collection.Add(snapshot, reflistCollection) != nil {
 			b.FailNow()
 		}
 	}
diff --git a/deb/snapshot_test.go b/deb/snapshot_test.go
index d27c42269..805ccc8e5 100644
--- a/deb/snapshot_test.go
+++ b/deb/snapshot_test.go
@@ -109,6 +109,7 @@ type SnapshotCollectionSuite struct {
 	snapshot1, snapshot2 *Snapshot
 	snapshot3, snapshot4 *Snapshot
 	collection           *SnapshotCollection
+	reflistCollection    *RefListCollection
 }
 
 var _ = Suite(&SnapshotCollectionSuite{})
@@ -116,6 +117,7 @@ var _ = Suite(&SnapshotCollectionSuite{})
 func (s *SnapshotCollectionSuite) SetUpTest(c *C) {
 	s.db, _ = goleveldb.NewOpenDB(c.MkDir())
 	s.collection = NewSnapshotCollection(s.db)
+	s.reflistCollection = NewRefListCollection(s.db)
 	s.SetUpPackages()
 
 	s.repo1, _ = NewRemoteRepo("yandex", "http://mirror.yandex.ru/debian/", "squeeze", []string{"main"}, []string{}, false, false, false)
@@ -143,10 +145,10 @@ func (s *SnapshotCollectionSuite) TestAddByNameByUUID(c *C) {
 	_, err := s.collection.ByName("snap1")
 	c.Assert(err, ErrorMatches, "*.not found")
 
-	c.Assert(s.collection.Add(s.snapshot1), IsNil)
-	c.Assert(s.collection.Add(s.snapshot1), ErrorMatches, ".*already exists")
+	c.Assert(s.collection.Add(s.snapshot1, s.reflistCollection), IsNil)
+	c.Assert(s.collection.Add(s.snapshot1, s.reflistCollection), ErrorMatches, ".*already exists")
 
-	c.Assert(s.collection.Add(s.snapshot2), IsNil)
+	c.Assert(s.collection.Add(s.snapshot2, s.reflistCollection), IsNil)
 
 	snapshot, err := s.collection.ByName("snap1")
 	c.Assert(err, IsNil)
@@ -167,20 +169,20 @@ func (s *SnapshotCollectionSuite) TestAddByNameByUUID(c *C) {
 }
 
 func (s *SnapshotCollectionSuite) TestUpdateLoadComplete(c *C) {
-	c.Assert(s.collection.Update(s.snapshot1), IsNil)
+	c.Assert(s.collection.Update(s.snapshot1, s.reflistCollection), IsNil)
 
 	collection := NewSnapshotCollection(s.db)
 	snapshot, err := collection.ByName("snap1")
 	c.Assert(err, IsNil)
 	c.Assert(snapshot.packageRefs, IsNil)
 
-	c.Assert(s.collection.LoadComplete(snapshot), IsNil)
+	c.Assert(s.collection.LoadComplete(snapshot, s.reflistCollection), IsNil)
 	c.Assert(snapshot.NumPackages(), Equals, 3)
 }
 
 func (s *SnapshotCollectionSuite) TestForEachAndLen(c *C) {
-	s.collection.Add(s.snapshot1)
-	s.collection.Add(s.snapshot2)
+	s.collection.Add(s.snapshot1, s.reflistCollection)
+	s.collection.Add(s.snapshot2, s.reflistCollection)
 
 	count := 0
 	err := s.collection.ForEach(func(*Snapshot) error {
@@ -200,10 +202,10 @@ func (s *SnapshotCollectionSuite) TestForEachAndLen(c *C) {
 }
 
 func (s *SnapshotCollectionSuite) TestForEachSorted(c *C) {
-	s.collection.Add(s.snapshot2)
-	s.collection.Add(s.snapshot1)
-	s.collection.Add(s.snapshot4)
-	s.collection.Add(s.snapshot3)
+	s.collection.Add(s.snapshot2, s.reflistCollection)
+	s.collection.Add(s.snapshot1, s.reflistCollection)
+	s.collection.Add(s.snapshot4, s.reflistCollection)
+	s.collection.Add(s.snapshot3, s.reflistCollection)
 
 	names := []string{}
 
@@ -217,8 +219,8 @@ func (s *SnapshotCollectionSuite) TestForEachSorted(c *C) {
 }
 
 func (s *SnapshotCollectionSuite) TestFindByRemoteRepoSource(c *C) {
-	c.Assert(s.collection.Add(s.snapshot1), IsNil)
-	c.Assert(s.collection.Add(s.snapshot2), IsNil)
+	c.Assert(s.collection.Add(s.snapshot1, s.reflistCollection), IsNil)
+	c.Assert(s.collection.Add(s.snapshot2, s.reflistCollection), IsNil)
 
 	c.Check(s.collection.ByRemoteRepoSource(s.repo1), DeepEquals, []*Snapshot{s.snapshot1})
 	c.Check(s.collection.ByRemoteRepoSource(s.repo2), DeepEquals, []*Snapshot{s.snapshot2})
@@ -229,10 +231,10 @@ func (s *SnapshotCollectionSuite) TestFindByRemoteRepoSource(c *C) {
 }
 
 func (s *SnapshotCollectionSuite) TestFindByLocalRepoSource(c *C) {
-	c.Assert(s.collection.Add(s.snapshot1), IsNil)
-	c.Assert(s.collection.Add(s.snapshot2), IsNil)
-	c.Assert(s.collection.Add(s.snapshot3), IsNil)
-	c.Assert(s.collection.Add(s.snapshot4), IsNil)
+	c.Assert(s.collection.Add(s.snapshot1, s.reflistCollection), IsNil)
+	c.Assert(s.collection.Add(s.snapshot2, s.reflistCollection), IsNil)
+	c.Assert(s.collection.Add(s.snapshot3, s.reflistCollection), IsNil)
+	c.Assert(s.collection.Add(s.snapshot4, s.reflistCollection), IsNil)
 
 	c.Check(s.collection.ByLocalRepoSource(s.lrepo1), DeepEquals, []*Snapshot{s.snapshot3})
 	c.Check(s.collection.ByLocalRepoSource(s.lrepo2), DeepEquals, []*Snapshot{s.snapshot4})
@@ -247,11 +249,11 @@ func (s *SnapshotCollectionSuite) TestFindSnapshotSource(c *C) {
 	snapshot4 := NewSnapshotFromRefList("snap4", []*Snapshot{s.snapshot1}, s.reflist, "desc2")
 	snapshot5 := NewSnapshotFromRefList("snap5", []*Snapshot{snapshot3}, s.reflist, "desc3")
 
-	c.Assert(s.collection.Add(s.snapshot1), IsNil)
-	c.Assert(s.collection.Add(s.snapshot2), IsNil)
-	c.Assert(s.collection.Add(snapshot3), IsNil)
-	c.Assert(s.collection.Add(snapshot4), IsNil)
-	c.Assert(s.collection.Add(snapshot5), IsNil)
+	c.Assert(s.collection.Add(s.snapshot1, s.reflistCollection), IsNil)
+	c.Assert(s.collection.Add(s.snapshot2, s.reflistCollection), IsNil)
+	c.Assert(s.collection.Add(snapshot3, s.reflistCollection), IsNil)
+	c.Assert(s.collection.Add(snapshot4, s.reflistCollection), IsNil)
+	c.Assert(s.collection.Add(snapshot5, s.reflistCollection), IsNil)
 
 	list := s.collection.BySnapshotSource(s.snapshot1)
 	sorter, _ := newSnapshotSorter("name", list)
@@ -263,8 +265,8 @@ func (s *SnapshotCollectionSuite) TestFindSnapshotSource(c *C) {
 }
 
 func (s *SnapshotCollectionSuite) TestDrop(c *C) {
-	s.collection.Add(s.snapshot1)
-	s.collection.Add(s.snapshot2)
+	s.collection.Add(s.snapshot1, s.reflistCollection)
+	s.collection.Add(s.snapshot2, s.reflistCollection)
 
 	snap, _ := s.collection.ByUUID(s.snapshot1.UUID)
 	c.Check(snap, Equals, s.snapshot1)
diff --git a/go.mod b/go.mod
index 311217cb3..478582cb1 100644
--- a/go.mod
+++ b/go.mod
@@ -8,6 +8,7 @@ require (
 	github.com/DisposaBoy/JsonConfigReader v0.0.0-20201129172854-99cf318d67e7
 	github.com/awalterschulze/gographviz v2.0.3+incompatible
 	github.com/cavaliergopher/grab/v3 v3.0.1
+	github.com/cespare/xxhash/v2 v2.2.0
 	github.com/cheggaaa/pb v1.0.29
 	github.com/gin-gonic/gin v1.9.1
 	github.com/go-playground/validator/v10 v10.15.4 // indirect
@@ -59,7 +60,6 @@ require (
 	github.com/aws/aws-sdk-go-v2/service/sts v1.23.2 // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/bytedance/sonic v1.10.1 // indirect
-	github.com/cespare/xxhash/v2 v2.2.0 // indirect
 	github.com/chenzhuoyu/base64x v0.0.0-20230717121745-296ad89f973d // indirect
 	github.com/chenzhuoyu/iasm v0.9.0 // indirect
 	github.com/cloudflare/circl v1.3.7 // indirect
diff --git a/go.sum b/go.sum
index 2de108cf8..eb90d955a 100644
--- a/go.sum
+++ b/go.sum
@@ -96,6 +96,7 @@ github.com/gin-contrib/sse v0.1.0/go.mod h1:RHrZQHXnP2xjPF+u1gW/2HnVO7nvIa9PG3Gm
 github.com/gin-gonic/gin v1.9.1 h1:4idEAncQnU5cB7BeOkPtxjfCSye0AAm1R0RVIqJ+Jmg=
 github.com/gin-gonic/gin v1.9.1/go.mod h1:hPrL7YrpYKXt5YId3A/Tnip5kqbEAP+KLuI3SUcPTeU=
 github.com/go-playground/assert/v2 v2.2.0 h1:JvknZsQTYeFEAhQwI4qEt9cyV5ONwRHC+lYKSsYSR8s=
+github.com/go-playground/assert/v2 v2.2.0/go.mod h1:VDjEfimB/XKnb+ZQfWdccd7VUvScMdVu0Titje2rxJ4=
 github.com/go-playground/locales v0.14.1 h1:EWaQ/wswjilfKLTECiXz7Rh+3BjFhfDFKv/oXslEjJA=
 github.com/go-playground/locales v0.14.1/go.mod h1:hxrqLVvrK65+Rwrd5Fc6F2O76J/NuW9t0sjnWqG1slY=
 github.com/go-playground/universal-translator v0.18.1 h1:Bcnm0ZwsGyWbCzImXv+pAJnYK9S473LQFuzCbDbfSFY=
@@ -115,6 +116,7 @@ github.com/golang/snappy v0.0.4/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEW
 github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.8/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
+github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
 github.com/google/uuid v1.0.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/google/uuid v1.2.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
@@ -337,6 +339,7 @@ gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7/go.mod h1:dt/ZhP58zS4L8KSrWD
 gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.8/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
+gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/system/Dockerfile b/system/Dockerfile
index 3b39488e5..c22ea3155 100644
--- a/system/Dockerfile
+++ b/system/Dockerfile
@@ -2,9 +2,9 @@ FROM debian:bookworm-slim
 
 RUN apt-get update -y && apt-get install -y --no-install-recommends curl gnupg && apt-get clean && rm -rf /var/lib/apt/lists/*
 
-RUN echo deb http://deb.debian.org/debian bookworm-backports main > /etc/apt/sources.list.d/backports.list
+#RUN echo deb http://deb.debian.org/debian bookworm-backports main > /etc/apt/sources.list.d/backports.list
 RUN apt-get update && \
-    apt-get install -y --no-install-recommends apg bzip2 xz-utils ca-certificates golang/bookworm-backports golang-go/bookworm-backports golang-doc/bookworm-backports golang-src/bookworm-backports make git python3 python3-requests-unixsocket python3-termcolor python3-swiftclient python3-boto && \
+    apt-get install -y --no-install-recommends apg bzip2 xz-utils ca-certificates golang golang-go golang-doc golang-src make git python3 python3-requests-unixsocket python3-termcolor python3-swiftclient python3-boto g++ && \
     apt-get clean && rm -rf /var/lib/apt/lists/*
 
 RUN useradd -m --shell /bin/sh --home-dir /var/lib/aptly aptly
diff --git a/system/t08_db/CleanupDB10Test_gold b/system/t08_db/CleanupDB10Test_gold
index 138adc294..faa25944e 100644
--- a/system/t08_db/CleanupDB10Test_gold
+++ b/system/t08_db/CleanupDB10Test_gold
@@ -1,6 +1,7 @@
 Loading mirrors, local repos, snapshots and published repos...
 Loading list of all packages...
 Deleting unreferenced packages (0)...
+Deleting unreferenced reflist buckets (0)...
 Building list of files referenced by packages...
 Building list of files in package pool...
 Deleting unreferenced files (0)...
diff --git a/system/t08_db/CleanupDB11Test_gold b/system/t08_db/CleanupDB11Test_gold
index be3767e9c..33be8b2a4 100644
--- a/system/t08_db/CleanupDB11Test_gold
+++ b/system/t08_db/CleanupDB11Test_gold
@@ -14,6 +14,7 @@ Loading mirrors:
 Loading local repos:
 Loading snapshots:
 Loading published repositories:
+Split 11 reflist(s) into 510 bucket(s) (123181 segment(s))
 Loading list of all packages...
 Deleting unreferenced packages (7)...
 List of package keys to delete:
@@ -24,6 +25,7 @@ List of package keys to delete:
  - Pi386 gnuplot-nox 4.6.1-1~maverick2 17785995cf0f815
  - Pi386 gnuplot-x11 4.6.1-1~maverick2 d42e1d0d2f23740
  - Psource gnuplot 4.6.1-1~maverick2 b8cd36358f5db41f
+Deleting unreferenced reflist buckets (0)...
 Building list of files referenced by packages...
 Building list of files in package pool...
 Deleting unreferenced files (9)...
diff --git a/system/t08_db/CleanupDB12Test_gold b/system/t08_db/CleanupDB12Test_gold
index 31da9b23c..4e88abc21 100644
--- a/system/t08_db/CleanupDB12Test_gold
+++ b/system/t08_db/CleanupDB12Test_gold
@@ -14,6 +14,7 @@ Loading mirrors:
 Loading local repos:
 Loading snapshots:
 Loading published repositories:
+Skipped splitting 11 reflist(s) into 510 bucket(s) (123181 segment(s)), as -dry-run has been requested.
 Loading list of all packages...
 Deleting unreferenced packages (7)...
 List of package keys to delete:
@@ -25,6 +26,7 @@ List of package keys to delete:
  - Pi386 gnuplot-x11 4.6.1-1~maverick2 d42e1d0d2f23740
  - Psource gnuplot 4.6.1-1~maverick2 b8cd36358f5db41f
 Skipped deletion, as -dry-run has been requested.
+Deleting unreferenced reflist buckets (0)...
 Building list of files referenced by packages...
 Building list of files in package pool...
 Deleting unreferenced files (9)...
diff --git a/system/t08_db/CleanupDB1Test_gold b/system/t08_db/CleanupDB1Test_gold
index 138adc294..faa25944e 100644
--- a/system/t08_db/CleanupDB1Test_gold
+++ b/system/t08_db/CleanupDB1Test_gold
@@ -1,6 +1,7 @@
 Loading mirrors, local repos, snapshots and published repos...
 Loading list of all packages...
 Deleting unreferenced packages (0)...
+Deleting unreferenced reflist buckets (0)...
 Building list of files referenced by packages...
 Building list of files in package pool...
 Deleting unreferenced files (0)...
diff --git a/system/t08_db/CleanupDB2Test_gold b/system/t08_db/CleanupDB2Test_gold
index 1f289e677..4e84de6a8 100644
--- a/system/t08_db/CleanupDB2Test_gold
+++ b/system/t08_db/CleanupDB2Test_gold
@@ -1,6 +1,7 @@
 Loading mirrors, local repos, snapshots and published repos...
 Loading list of all packages...
 Deleting unreferenced packages (73270)...
+Deleting unreferenced reflist buckets (0)...
 Building list of files referenced by packages...
 Building list of files in package pool...
 Deleting unreferenced files (0)...
diff --git a/system/t08_db/CleanupDB3Test_gold b/system/t08_db/CleanupDB3Test_gold
index 73279e145..73c82f87d 100644
--- a/system/t08_db/CleanupDB3Test_gold
+++ b/system/t08_db/CleanupDB3Test_gold
@@ -1,6 +1,7 @@
 Loading mirrors, local repos, snapshots and published repos...
 Loading list of all packages...
 Deleting unreferenced packages (7)...
+Deleting unreferenced reflist buckets (0)...
 Building list of files referenced by packages...
 Building list of files in package pool...
 Deleting unreferenced files (9)...
diff --git a/system/t08_db/CleanupDB4Test_gold b/system/t08_db/CleanupDB4Test_gold
index 138adc294..faa25944e 100644
--- a/system/t08_db/CleanupDB4Test_gold
+++ b/system/t08_db/CleanupDB4Test_gold
@@ -1,6 +1,7 @@
 Loading mirrors, local repos, snapshots and published repos...
 Loading list of all packages...
 Deleting unreferenced packages (0)...
+Deleting unreferenced reflist buckets (0)...
 Building list of files referenced by packages...
 Building list of files in package pool...
 Deleting unreferenced files (0)...
diff --git a/system/t08_db/CleanupDB5Test_gold b/system/t08_db/CleanupDB5Test_gold
index 73279e145..47bba4e2b 100644
--- a/system/t08_db/CleanupDB5Test_gold
+++ b/system/t08_db/CleanupDB5Test_gold
@@ -1,6 +1,7 @@
 Loading mirrors, local repos, snapshots and published repos...
 Loading list of all packages...
 Deleting unreferenced packages (7)...
+Deleting unreferenced reflist buckets (1)...
 Building list of files referenced by packages...
 Building list of files in package pool...
 Deleting unreferenced files (9)...
diff --git a/system/t08_db/CleanupDB6Test_gold b/system/t08_db/CleanupDB6Test_gold
index 138adc294..faa25944e 100644
--- a/system/t08_db/CleanupDB6Test_gold
+++ b/system/t08_db/CleanupDB6Test_gold
@@ -1,6 +1,7 @@
 Loading mirrors, local repos, snapshots and published repos...
 Loading list of all packages...
 Deleting unreferenced packages (0)...
+Deleting unreferenced reflist buckets (0)...
 Building list of files referenced by packages...
 Building list of files in package pool...
 Deleting unreferenced files (0)...
diff --git a/system/t08_db/CleanupDB7Test_gold b/system/t08_db/CleanupDB7Test_gold
index 138adc294..faa25944e 100644
--- a/system/t08_db/CleanupDB7Test_gold
+++ b/system/t08_db/CleanupDB7Test_gold
@@ -1,6 +1,7 @@
 Loading mirrors, local repos, snapshots and published repos...
 Loading list of all packages...
 Deleting unreferenced packages (0)...
+Deleting unreferenced reflist buckets (0)...
 Building list of files referenced by packages...
 Building list of files in package pool...
 Deleting unreferenced files (0)...
diff --git a/system/t08_db/CleanupDB8Test_gold b/system/t08_db/CleanupDB8Test_gold
index f769f203f..43ebe9aaa 100644
--- a/system/t08_db/CleanupDB8Test_gold
+++ b/system/t08_db/CleanupDB8Test_gold
@@ -1,6 +1,7 @@
 Loading mirrors, local repos, snapshots and published repos...
 Loading list of all packages...
 Deleting unreferenced packages (4)...
+Deleting unreferenced reflist buckets (1)...
 Building list of files referenced by packages...
 Building list of files in package pool...
 Deleting unreferenced files (6)...
diff --git a/system/t08_db/CleanupDB9Test_gold b/system/t08_db/CleanupDB9Test_gold
index 138adc294..faa25944e 100644
--- a/system/t08_db/CleanupDB9Test_gold
+++ b/system/t08_db/CleanupDB9Test_gold
@@ -1,6 +1,7 @@
 Loading mirrors, local repos, snapshots and published repos...
 Loading list of all packages...
 Deleting unreferenced packages (0)...
+Deleting unreferenced reflist buckets (0)...
 Building list of files referenced by packages...
 Building list of files in package pool...
 Deleting unreferenced files (0)...
diff --git a/utils/utils.go b/utils/utils.go
index 598dc7c8f..4d4734fc7 100644
--- a/utils/utils.go
+++ b/utils/utils.go
@@ -10,13 +10,13 @@ import (
 
 // DirIsAccessible verifies that directory exists and is accessible
 func DirIsAccessible(filename string) error {
-	_, err := os.Stat(filename)
+	fileStat, err := os.Stat(filename)
 	if err != nil {
 		if !os.IsNotExist(err) {
 			return fmt.Errorf("error checking directory '%s': %s", filename, err)
 		}
 	} else {
-		if unix.Access(filename, unix.W_OK) != nil {
+		if fileStat.Mode().Perm() == 0000 || unix.Access(filename, unix.W_OK) != nil {
 			return fmt.Errorf("'%s' is inaccessible, check access rights", filename)
 		}
 	}
diff --git a/utils/utils_test.go b/utils/utils_test.go
index c9838da69..17c46f132 100644
--- a/utils/utils_test.go
+++ b/utils/utils_test.go
@@ -32,5 +32,9 @@ func (s *UtilsSuite) TestDirIsAccessibleNotExist(c *C) {
 }
 
 func (s *UtilsSuite) TestDirIsAccessibleNotAccessible(c *C) {
-	c.Check(DirIsAccessible(s.tempfile.Name()).Error(), Equals, fmt.Errorf("'%s' is inaccessible, check access rights", s.tempfile.Name()).Error())
+	accessible := DirIsAccessible(s.tempfile.Name())
+	if accessible == nil {
+            c.Fatalf("Test dir should not be accessible: %s", s.tempfile.Name())
+        }
+	c.Check(accessible.Error(), Equals, fmt.Errorf("'%s' is inaccessible, check access rights", s.tempfile.Name()).Error())
 }