Do not return stats in Backend.ListDatabases (#3588)

internal/backends/backend.go

@@ -15,9 +15,11 @@
 package backends
 
 import (
+	"cmp"
 	"context"
 
 	"github.com/prometheus/client_golang/prometheus"
+	"golang.org/x/exp/slices"
 
 	"github.com/FerretDB/FerretDB/internal/clientconn/conninfo"
 	"github.com/FerretDB/FerretDB/internal/util/must"
@@ -131,16 +133,21 @@ type ListDatabasesResult struct {
 // DatabaseInfo represents information about a single database.
 type DatabaseInfo struct {
 	Name string
-	Size int64
 }
 
-// ListDatabases returns a list of databases.
+// ListDatabases returns a list of databases sorted by name.
 func (bc *backendContract) ListDatabases(ctx context.Context, params *ListDatabasesParams) (*ListDatabasesResult, error) {
 	defer observability.FuncCall(ctx)()
 
 	res, err := bc.b.ListDatabases(ctx, params)
 	checkError(err)
 
+	if res != nil && len(res.Databases) > 0 {
+		must.BeTrue(slices.IsSortedFunc(res.Databases, func(a, b DatabaseInfo) int {
+			return cmp.Compare(a.Name, b.Name)
+		}))
+	}
+
 	return res, err
 }
 

internal/backends/collection.go

@@ -241,7 +241,8 @@ type IndexSize struct {
 	Size int64
 }
 
-// Stats returns statistics about the collection.
+// Stats returns statistic estimations about the collection.
+// All returned values are not exact, but might be more accurate when Stats is called with `Refresh: true`.
 //
 // The errors for non-existing database and non-existing collection are the same.
 func (cc *collectionContract) Stats(ctx context.Context, params *CollectionStatsParams) (*CollectionStatsResult, error) {
@@ -296,7 +297,7 @@ type IndexKeyPair struct {
 	Descending bool
 }
 
-// ListIndexes returns information about indexes in the database.
+// ListIndexes returns a list of collection indexes.
 //
 // The errors for non-existing database and non-existing collection are the same.
 func (cc *collectionContract) ListIndexes(ctx context.Context, params *ListIndexesParams) (*ListIndexesResult, error) {
@@ -305,6 +306,13 @@ func (cc *collectionContract) ListIndexes(ctx context.Context, params *ListIndex
 	res, err := cc.c.ListIndexes(ctx, params)
 	checkError(err, ErrorCodeCollectionDoesNotExist)
 
+	// TODO https://github.com/FerretDB/FerretDB/issues/3589
+	// if res != nil && len(res.Indexes) > 0 {
+	// 	must.BeTrue(slices.IsSortedFunc(res.Indexes, func(a, b IndexInfo) int {
+	// 		return cmp.Compare(a.Name, b.Name)
+	// 	}))
+	// }
+
 	return res, err
 }
 

internal/backends/database.go

@@ -15,8 +15,11 @@
 package backends
 
 import (
+	"cmp"
 	"context"
 
+	"golang.org/x/exp/slices"
+
 	"github.com/FerretDB/FerretDB/internal/util/must"
 	"github.com/FerretDB/FerretDB/internal/util/observability"
 )
@@ -94,15 +97,23 @@ func (ci *CollectionInfo) Capped() bool {
 	return ci.CappedSize > 0 || ci.CappedDocuments > 0
 }
 
-// ListCollections returns information about collections in the database.
+// ListCollections returns a list collections in the database sorted by name.
 //
 // Database may not exist; that's not an error.
+//
+// Contract ensures that returned list is sorted by name.
 func (dbc *databaseContract) ListCollections(ctx context.Context, params *ListCollectionsParams) (*ListCollectionsResult, error) {
 	defer observability.FuncCall(ctx)()
 
 	res, err := dbc.db.ListCollections(ctx, params)
 	checkError(err)
 
+	if res != nil && len(res.Collections) > 0 {
+		must.BeTrue(slices.IsSortedFunc(res.Collections, func(a, b CollectionInfo) int {
+			return cmp.Compare(a.Name, b.Name)
+		}))
+	}
+
 	return res, err
 }
 
@@ -199,7 +210,8 @@ type DatabaseStatsResult struct {
 	SizeCollections int64
 }
 
-// Stats returns statistics about the database.
+// Stats returns statistic estimations about the database.
+// All returned values are not exact, but might be more accurate when Stats is called with `Refresh: true`.
 func (dbc *databaseContract) Stats(ctx context.Context, params *DatabaseStatsParams) (*DatabaseStatsResult, error) {
 	defer observability.FuncCall(ctx)()
 

internal/backends/postgresql/backend.go

@@ -130,24 +130,8 @@ func (b *backend) ListDatabases(ctx context.Context, params *backends.ListDataba
 	}
 
 	for i, dbName := range list {
-		db, err := b.Database(dbName)
-		if err != nil {
-			return nil, lazyerrors.Error(err)
-		}
-
-		stats, err := db.Stats(ctx, new(backends.DatabaseStatsParams))
-		if backends.ErrorCodeIs(err, backends.ErrorCodeDatabaseDoesNotExist) {
-			stats = new(backends.DatabaseStatsResult)
-			err = nil
-		}
-
-		if err != nil {
-			return nil, lazyerrors.Error(err)
-		}
-
 		res.Databases[i] = backends.DatabaseInfo{
 			Name: dbName,
-			Size: stats.SizeTotal,
 		}
 	}
 

internal/backends/postgresql/collection.go

@@ -454,6 +454,11 @@ func (c *collection) ListIndexes(ctx context.Context, params *backends.ListIndex
 		}
 	}
 
+	// TODO https://github.com/FerretDB/FerretDB/issues/3589
+	// slices.SortFunc(res.Indexes, func(a, b backends.IndexInfo) int {
+	// 	return cmp.Compare(a.Name, b.Name)
+	// })
+
 	return &res, nil
 }
 

internal/backends/sqlite/backend.go

@@ -106,24 +106,8 @@ func (b *backend) ListDatabases(ctx context.Context, params *backends.ListDataba
 	}
 
 	for i, dbName := range list {
-		db, err := b.Database(dbName)
-		if err != nil {
-			return nil, lazyerrors.Error(err)
-		}
-
-		stats, err := db.Stats(ctx, new(backends.DatabaseStatsParams))
-		if backends.ErrorCodeIs(err, backends.ErrorCodeDatabaseDoesNotExist) {
-			stats = new(backends.DatabaseStatsResult)
-			err = nil
-		}
-
-		if err != nil {
-			return nil, lazyerrors.Error(err)
-		}
-
 		res.Databases[i] = backends.DatabaseInfo{
 			Name: dbName,
-			Size: stats.SizeTotal,
 		}
 	}
 

internal/backends/sqlite/collection.go

@@ -452,6 +452,11 @@ func (c *collection) ListIndexes(ctx context.Context, params *backends.ListIndex
 		}
 	}
 
+	// TODO https://github.com/FerretDB/FerretDB/issues/3589
+	// slices.SortFunc(res.Indexes, func(a, b backends.IndexInfo) int {
+	// 	return cmp.Compare(a.Name, b.Name)
+	// })
+
 	return &res, nil
 }
 

internal/handlers/sqlite/msg_aggregate.go

@@ -15,13 +15,16 @@
 package sqlite
 
 import (
+	"cmp"
 	"context"
 	"errors"
 	"fmt"
 	"math"
 	"os"
 	"time"
 
+	"golang.org/x/exp/slices"
+
 	"github.com/FerretDB/FerretDB/internal/backends"
 	"github.com/FerretDB/FerretDB/internal/clientconn/conninfo"
 	"github.com/FerretDB/FerretDB/internal/clientconn/cursor"
@@ -402,17 +405,10 @@ func processStagesStats(ctx context.Context, closer *iterator.MultiCloser, p *st
 			return nil, lazyerrors.Error(err)
 		}
 
-		var found bool
-
-		for _, cInfo := range cList.Collections {
-			if cInfo.Name == p.cName {
-				found = true
-				break
-			}
-		}
-
-		if !found {
-			cInfo = backends.CollectionInfo{}
+		if i, found := slices.BinarySearchFunc(cList.Collections, p.cName, func(e backends.CollectionInfo, t string) int {
+			return cmp.Compare(e.Name, t)
+		}); found {
+			cInfo = cList.Collections[i]
 		}
 
 		var iList *backends.ListIndexesResult

internal/handlers/sqlite/msg_collstats.go

@@ -15,9 +15,12 @@
 package sqlite
 
 import (
+	"cmp"
 	"context"
 	"fmt"
 
+	"golang.org/x/exp/slices"
+
 	"github.com/FerretDB/FerretDB/internal/backends"
 	"github.com/FerretDB/FerretDB/internal/handlers/common"
 	"github.com/FerretDB/FerretDB/internal/handlers/commonerrors"
@@ -76,23 +79,16 @@ func (h *Handler) MsgCollStats(ctx context.Context, msg *wire.OpMsg) (*wire.OpMs
 		return nil, lazyerrors.Error(err)
 	}
 
-	list, err := db.ListCollections(ctx, new(backends.ListCollectionsParams))
+	collections, err := db.ListCollections(ctx, new(backends.ListCollectionsParams))
 	if err != nil {
 		return nil, lazyerrors.Error(err)
 	}
 
-	var found bool
 	var cInfo backends.CollectionInfo
-
-	for _, cInfo := range list.Collections {
-		if cInfo.Name == collection {
-			found = true
-			break
-		}
-	}
-
-	if !found {
-		cInfo = backends.CollectionInfo{}
+	if i, found := slices.BinarySearchFunc(collections.Collections, collection, func(e backends.CollectionInfo, t string) int {
+		return cmp.Compare(e.Name, t)
+	}); found {
+		cInfo = collections.Collections[i]
 	}
 
 	indexes, err := c.ListIndexes(ctx, new(backends.ListIndexesParams))

internal/handlers/sqlite/msg_listdatabases.go

@@ -17,6 +17,8 @@ package sqlite
 import (
 	"context"
 
+	"go.uber.org/zap"
+
 	"github.com/FerretDB/FerretDB/internal/handlers/common"
 	"github.com/FerretDB/FerretDB/internal/handlers/commonparams"
 	"github.com/FerretDB/FerretDB/internal/types"
@@ -56,14 +58,34 @@ func (h *Handler) MsgListDatabases(ctx context.Context, msg *wire.OpMsg) (*wire.
 
 	databases := types.MakeArray(len(res.Databases))
 
-	for _, db := range res.Databases {
+	for _, dbInfo := range res.Databases {
+		if nameOnly {
+			databases.Append(must.NotFail(types.NewDocument(
+				"name", dbInfo.Name,
+			)))
+
+			continue
+		}
+
+		db, err := h.b.Database(dbInfo.Name)
+		if err != nil {
+			h.L.Warn("Failed to get database", zap.Error(err))
+			continue
+		}
+
+		stats, err := db.Stats(ctx, nil)
+		if err != nil {
+			h.L.Warn("Failed to get database stats", zap.Error(err))
+			continue
+		}
+
 		d := must.NotFail(types.NewDocument(
-			"name", db.Name,
-			"sizeOnDisk", db.Size,
-			"empty", db.Size == 0,
+			"name", dbInfo.Name,
+			"sizeOnDisk", stats.SizeTotal,
+			"empty", stats.SizeTotal == 0,
 		))
 
-		totalSize += db.Size
+		totalSize += stats.SizeTotal
 
 		matches, err := common.FilterDocument(d, filter)
 		if err != nil {
@@ -74,12 +96,6 @@ func (h *Handler) MsgListDatabases(ctx context.Context, msg *wire.OpMsg) (*wire.
 			continue
 		}
 
-		if nameOnly {
-			d = must.NotFail(types.NewDocument(
-				"name", db.Name,
-			))
-		}
-
 		databases.Append(d)
 	}