feat: MMR Reranking for Document and Memory Search (#232)

* mmr memory search

* remove withMMR from documents

* update swagger

* mmr for document search

docs/swagger.yaml

@@ -159,8 +159,12 @@ definitions:
       metadata:
         additionalProperties: true
         type: object
+      mmr_lambda:
+        type: number
       text:
         type: string
+      type:
+        $ref: '#/definitions/models.SearchType'
     type: object
   models.GetDocumentListRequest:
     properties:
@@ -190,13 +194,21 @@ definitions:
       metadata:
         additionalProperties: true
         type: object
+      mmr_lambda:
+        type: number
       text:
         type: string
+      type:
+        $ref: '#/definitions/models.SearchType'
     type: object
   models.MemorySearchResult:
     properties:
       dist:
         type: number
+      embedding:
+        items:
+          type: number
+        type: array
       message:
         $ref: '#/definitions/models.Message'
       metadata:
@@ -225,6 +237,14 @@ definitions:
       uuid:
         type: string
     type: object
+  models.SearchType:
+    enum:
+    - similarity
+    - mmr
+    type: string
+    x-enum-varnames:
+    - SearchTypeSimilarity
+    - SearchTypeMMR
   models.Session:
     properties:
       created_at:
@@ -910,10 +930,6 @@ paths:
         in: query
         name: limit
         type: integer
-      - description: Use MMR to rerank the search results. Not Implemented
-        in: query
-        name: mmr
-        type: boolean
       - description: Search criteria
         in: body
         name: searchPayload

go.mod

@@ -28,7 +28,6 @@ require (
 	github.com/uptrace/bun v1.1.16
 	github.com/uptrace/bun/dialect/pgdialect v1.1.16
 	github.com/uptrace/bun/driver/pgdriver v1.1.16
-	gonum.org/v1/gonum v0.14.0
 )
 
 require (
@@ -40,12 +39,14 @@ require (
 	github.com/tmc/langchaingo v0.0.0-20230929160525-e16b77704b8d
 	github.com/uptrace/bun/dbfixture v1.1.16
 	github.com/uptrace/bun/extra/bundebug v1.1.16
+	github.com/viterin/vek v0.4.2
 	gopkg.in/yaml.v3 v3.0.1
 )
 
 require (
 	github.com/KyleBanks/depth v1.2.1 // indirect
 	github.com/Masterminds/goutils v1.1.1 // indirect
+	github.com/chewxy/math32 v1.10.1 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/decred/dcrd/dcrec/secp256k1/v4 v4.2.0 // indirect
 	github.com/dlclark/regexp2 v1.10.0 // indirect
@@ -92,13 +93,15 @@ require (
 	github.com/subosito/gotenv v1.6.0 // indirect
 	github.com/sv-tools/openapi v0.2.2 // indirect
 	github.com/tmthrgd/go-hex v0.0.0-20190904060850-447a3041c3bc // indirect
+	github.com/viterin/partial v1.1.0 // indirect
 	github.com/vmihailenco/msgpack/v5 v5.3.5 // indirect
 	github.com/vmihailenco/tagparser/v2 v2.0.0 // indirect
 	golang.org/x/crypto v0.14.0 // indirect
+	golang.org/x/exp v0.0.0-20231006140011-7918f672742d // indirect
 	golang.org/x/net v0.17.0 // indirect
 	golang.org/x/sys v0.13.0 // indirect
 	golang.org/x/text v0.13.0 // indirect
-	golang.org/x/tools v0.13.0 // indirect
+	golang.org/x/tools v0.14.0 // indirect
 	gopkg.in/ini.v1 v1.67.0 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	mellium.im/sasl v0.3.1 // indirect

go.sum

@@ -56,6 +56,8 @@ github.com/avast/retry-go/v4 v4.5.0/go.mod h1:7hLEXp0oku2Nir2xBAsg0PTphp9z71bN5A
 github.com/brianvoe/gofakeit/v6 v6.23.2 h1:lVde18uhad5wII/f5RMVFLtdQNE0HaGFuBUXmYKk8i8=
 github.com/brianvoe/gofakeit/v6 v6.23.2/go.mod h1:Ow6qC71xtwm79anlwKRlWZW6zVq9D2XHE4QSSMP/rU8=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
+github.com/chewxy/math32 v1.10.1 h1:LFpeY0SLJXeaiej/eIp2L40VYfscTvKh/FSEZ68uMkU=
+github.com/chewxy/math32 v1.10.1/go.mod h1:dOB2rcuFrCn6UHrze36WSLVPKtzPMRAQvBvUwkSsLqs=
 github.com/chi-middleware/logrus-logger v0.2.0 h1:Do3vcVSRsLh7zSRKxsVg5Kr5//rTqytwprCR1HzVqT8=
 github.com/chi-middleware/logrus-logger v0.2.0/go.mod h1:ie/rvKsXrtqqsnJd3qtSEnLxgCs1I758WYmHdv6CRt0=
 github.com/chzyer/logex v1.1.10/go.mod h1:+Ywpsq7O8HXn0nuIou7OrIPyXbp3wmkHB+jjWRnGsAI=
@@ -347,6 +349,10 @@ github.com/uptrace/bun/driver/pgdriver v1.1.16 h1:b/NiSXk6Ldw7KLfMLbOqIkm4odHd7Q
 github.com/uptrace/bun/driver/pgdriver v1.1.16/go.mod h1:Rmfbc+7lx1z/umjMyAxkOHK81LgnGj71XC5YpA6k1vU=
 github.com/uptrace/bun/extra/bundebug v1.1.16 h1:SgicRQGtnjhrIhlYOxdkOm1Em4s6HykmT3JblHnoTBM=
 github.com/uptrace/bun/extra/bundebug v1.1.16/go.mod h1:SkiOkfUirBiO1Htc4s5bQKEq+JSeU1TkBVpMsPz2ePM=
+github.com/viterin/partial v1.1.0 h1:iH1l1xqBlapXsYzADS1dcbizg3iQUKTU1rbwkHv/80E=
+github.com/viterin/partial v1.1.0/go.mod h1:oKGAo7/wylWkJTLrWX8n+f4aDPtQMQ6VG4dd2qur5QA=
+github.com/viterin/vek v0.4.2 h1:Vyv04UjQT6gcjEFX82AS9ocgNbAJqsHviheIBdPlv5U=
+github.com/viterin/vek v0.4.2/go.mod h1:A4JRAe8OvbhdzBL5ofzjBS0J29FyUrf95tQogvtHHUc=
 github.com/vmihailenco/bufpool v0.1.11 h1:gOq2WmBrq0i2yW5QJ16ykccQ4wH9UyEsgLm6czKAd94=
 github.com/vmihailenco/bufpool v0.1.11/go.mod h1:AFf/MOy3l2CFTKbxwt0mp2MwnqjNEs5H/UxrkA5jxTQ=
 github.com/vmihailenco/msgpack/v5 v5.3.4/go.mod h1:7xyJ9e+0+9SaZT0Wt1RGleJXzli6Q/V5KbhBonMG9jc=
@@ -389,8 +395,8 @@ golang.org/x/exp v0.0.0-20191227195350-da58074b4299/go.mod h1:2RIsYlXP63K8oxa1u0
 golang.org/x/exp v0.0.0-20200119233911-0405dc783f0a/go.mod h1:2RIsYlXP63K8oxa1u096TMicItID8zy7Y6sNkU49FU4=
 golang.org/x/exp v0.0.0-20200207192155-f17229e696bd/go.mod h1:J/WKrq2StrnmMY6+EHIKF9dgMWnmCNThgcyBT1FY9mM=
 golang.org/x/exp v0.0.0-20200224162631-6cc2880d07d6/go.mod h1:3jZMyOhIsHpP37uCMkUooju7aAi5cS1Q23tOzKc+0MU=
-golang.org/x/exp v0.0.0-20230510235704-dd950f8aeaea h1:vLCWI/yYrdEHyN2JzIzPO3aaQJHQdp89IZBA/+azVC4=
-golang.org/x/exp v0.0.0-20230510235704-dd950f8aeaea/go.mod h1:V1LtkGg67GoY2N1AnLN78QLrzxkLyJw7RJb1gzOOz9w=
+golang.org/x/exp v0.0.0-20231006140011-7918f672742d h1:jtJma62tbqLibJ5sFQz8bKtEM8rJBtfilJ2qTU199MI=
+golang.org/x/exp v0.0.0-20231006140011-7918f672742d/go.mod h1:ldy0pHrwJyGW56pPQzzkH36rKxoZW1tw7ZJpeKx+hdo=
 golang.org/x/image v0.0.0-20190227222117-0694c2d4d067/go.mod h1:kZ7UVZpmo3dzQBMxlp+ypCbDeSB+sBbTgSJuh5dn5js=
 golang.org/x/image v0.0.0-20190802002840-cff245a6509b/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
 golang.org/x/lint v0.0.0-20181026193005-c67002cb31c3/go.mod h1:UVdnD1Gm6xHRNCYTkRU2/jEulfH38KcIWyp/GAMgvoE=
@@ -416,8 +422,8 @@ golang.org/x/mod v0.4.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/mod v0.4.1/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
 golang.org/x/mod v0.8.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
-golang.org/x/mod v0.12.0 h1:rmsUpXtvNzj340zd98LZ4KntptpfRHwpFOHG188oHXc=
-golang.org/x/mod v0.12.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
+golang.org/x/mod v0.13.0 h1:I/DsJXRlw/8l/0c24sM9yb0T4z9liZTduXvdAWYiysY=
+golang.org/x/mod v0.13.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
 golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20180826012351-8a410e7b638d/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20190108225652-1e06a53dbb7e/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
@@ -599,14 +605,12 @@ golang.org/x/tools v0.0.0-20210108195828-e2f9c7f1fc8e/go.mod h1:emZCQorbCU4vsT4f
 golang.org/x/tools v0.1.0/go.mod h1:xkSsbof2nBLbhDlRMhhhyNLN/zl3eTqcnHD5viDpcZ0=
 golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
 golang.org/x/tools v0.6.0/go.mod h1:Xwgl3UAJ/d3gWutnCtw505GrjyAbvKui8lOU390QaIU=
-golang.org/x/tools v0.13.0 h1:Iey4qkscZuv0VvIt8E0neZjtPVQFSc870HQ448QgEmQ=
-golang.org/x/tools v0.13.0/go.mod h1:HvlwmtVNQAhOuCjW7xxvovg8wbNq7LwfXh/k7wXUl58=
+golang.org/x/tools v0.14.0 h1:jvNa2pY0M4r62jkRQ6RwEZZyPcymeL9XZMLBbV7U2nc=
+golang.org/x/tools v0.14.0/go.mod h1:uYBEerGOWcJyEORxN+Ek8+TT266gXkNlHdJBwexUsBg=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-gonum.org/v1/gonum v0.14.0 h1:2NiG67LD1tEH0D7kM+ps2V+fXmsAnpUeec7n8tcr4S0=
-gonum.org/v1/gonum v0.14.0/go.mod h1:AoWeoz0becf9QMWtE8iWXNXc27fK4fNeHNf/oMejGfU=
 google.golang.org/api v0.4.0/go.mod h1:8k5glujaEP+g9n7WNsDg8QP6cUVNI86fCNMcbazEtwE=
 google.golang.org/api v0.7.0/go.mod h1:WtwebWUNSVBH/HAw79HIFXZNqEvBhG+Ra+ax0hx3E3M=
 google.golang.org/api v0.8.0/go.mod h1:o4eAsZoiT+ibD93RtjEohWalFOjRDx6CVaqeizhEnKg=

pkg/models/document.go

@@ -83,7 +83,7 @@ type Document struct {
 	Embedding []float32 `bun:"type:vector,nullzero" json:"embedding,omitempty"`
 }
 
-type SearchDocumentQuery struct {
+type SearchDocumentResult struct {
 	*Document
 	Score float64 `json:"score" bun:"score"`
 }

pkg/models/documentstore.go

@@ -70,7 +70,6 @@ type DocumentStore[T any] interface {
 		ctx context.Context,
 		query *DocumentSearchPayload,
 		limit int,
-		withMMR bool, // withMMR is used to enable/disable the Maximal Marginal Relevance algorithm for search results.
 		pageNumber int,
 		pageSize int,
 	) (*DocumentSearchResultPage, error)

pkg/models/search.go

@@ -1,22 +1,34 @@
 package models
 
+type SearchType string
+
+const (
+	SearchTypeSimilarity SearchType = "similarity"
+	SearchTypeMMR        SearchType = "mmr"
+)
+
 type MemorySearchResult struct {
-	Message  *Message               `json:"message"`
-	Summary  *Summary               `json:"summary"` // reserved for future use
-	Metadata map[string]interface{} `json:"metadata,omitempty"`
-	Dist     float64                `json:"dist"`
+	Message   *Message               `json:"message"`
+	Summary   *Summary               `json:"summary"` // reserved for future use
+	Metadata  map[string]interface{} `json:"metadata,omitempty"`
+	Dist      float64                `json:"dist"`
+	Embedding []float32              `json:"embedding"`
 }
 
 type MemorySearchPayload struct {
-	Text     string                 `json:"text"`
-	Metadata map[string]interface{} `json:"metadata,omitempty"`
+	Text      string                 `json:"text"`
+	Metadata  map[string]interface{} `json:"metadata,omitempty"`
+	Type      SearchType             `json:"type"`
+	MMRLambda float32                `json:"mmr_lambda,omitempty"`
 }
 
 type DocumentSearchPayload struct {
 	CollectionName string                 `json:"collection_name"`
 	Text           string                 `json:"text,omitempty"`
 	Embedding      []float32              `json:"embedding,omitempty"`
 	Metadata       map[string]interface{} `json:"metadata,omitempty"`
+	Type           SearchType             `json:"type"`
+	MMRLambda      float32                `json:"mmr_lambda,omitempty"`
 }
 
 type DocumentSearchResult struct {

pkg/search/mmr.go

@@ -1,120 +1,92 @@
 package search
 
 import (
+	"errors"
 	"fmt"
 	"math"
 
-	"gonum.org/v1/gonum/floats"
-
-	"gonum.org/v1/gonum/mat"
+	"github.com/getzep/zep/internal"
+	"github.com/viterin/vek"
+	"github.com/viterin/vek/vek32"
 )
 
-// CosineSimilarity calculates the cosine similarity between two vectors.
-// The vectors must be of the same length.
-func CosineSimilarity(X, Y *mat.Dense) (*mat.Dense, error) { // nolint: gocritic
-	rX, cX := X.Dims()
-	rY, cY := Y.Dims()
-
-	if rX == 0 || rY == 0 {
-		return mat.NewDense(0, 0, nil), nil
-	}
-
-	if cX != cY {
-		return nil, fmt.Errorf(
-			"number of columns in X and Y must be the same. X has shape [%d, %d] and Y has shape [%d, %d]",
-			rX,
-			cX,
-			rY,
-			cY,
-		)
-	}
-
-	Xnorm := mat.NewVecDense(rX, nil)
-	Ynorm := mat.NewVecDense(rY, nil)
-
-	for i := 0; i < rX; i++ {
-		Xnorm.SetVec(i, mat.Norm(X.RowView(i), 2))
-	}
-
-	for i := 0; i < rY; i++ {
-		Ynorm.SetVec(i, mat.Norm(Y.RowView(i), 2))
-	}
+var log = internal.GetLogger()
 
-	var XT mat.Dense
-	XT.CloneFrom(X.T())
-
-	similarity := mat.NewDense(rX, rY, nil)
-	similarity.Product(X, &XT)
+func init() {
+	log.Infof("MMR acceleration status: %v", vek.Info())
+}
 
-	for i := 0; i < rX; i++ {
-		for j := 0; j < rY; j++ {
-			val := similarity.At(i, j) / (Xnorm.AtVec(i) * Ynorm.AtVec(j))
-			if math.IsNaN(val) || math.IsInf(val, 0) {
-				val = 0.0
+// pairwiseCosineSimilarity takes two matrices of vectors and returns a matrix, where
+// the value at [i][j] is the cosine similarity between the ith vector in matrix1 and
+// the jth vector in matrix2.
+func pairwiseCosineSimilarity(matrix1 [][]float32, matrix2 [][]float32) ([][]float32, error) {
+	result := make([][]float32, len(matrix1))
+	for i, vec1 := range matrix1 {
+		result[i] = make([]float32, len(matrix2))
+		for j, vec2 := range matrix2 {
+			if len(vec1) != len(vec2) {
+				return nil, fmt.Errorf("vector lengths do not match: %d != %d", len(vec1), len(vec2))
 			}
-			similarity.Set(i, j, val)
+			result[i][j] = vek32.CosineSimilarity(vec1, vec2)
 		}
 	}
-
-	return similarity, nil
+	return result, nil
 }
 
 // MaximalMarginalRelevance implements the Maximal Marginal Relevance algorithm.
 // It takes a query embedding, a list of embeddings, a lambda multiplier, and a
 // number of results to return. It returns a list of indices of the embeddings
 // that are most relevant to the query.
-// This is a relatively naive and unoptimized implementation of MMR. :-/
 // See https://www.cs.cmu.edu/~jgc/publication/The_Use_MMR_Diversity_Based_LTMIR_1998.pdf
-func MaximalMarginalRelevance(
-	queryEmbedding *mat.Dense,
-	embeddingList *mat.Dense,
-	lambdaMult float64,
-	k int,
-) ([]int, error) {
-	rEmbed, _ := embeddingList.Dims()
-	if k <= 0 || rEmbed == 0 {
+// Implementation borrowed from LangChain
+// https://github.com/langchain-ai/langchain/blob/4a2f0c51a116cc3141142ea55254e270afb6acde/libs/langchain/langchain/vectorstores/utils.py
+func MaximalMarginalRelevance(queryEmbedding []float32, embeddingList [][]float32, lambdaMult float32, k int) ([]int, error) {
+	// if either k or the length of the embedding list is 0, return an empty list
+	if min(k, len(embeddingList)) <= 0 {
 		return []int{}, nil
 	}
 
-	var mostSimilar int
-	var bestScore float64
-	var idxToAdd int
+	// We expect the query embedding and the embeddings in the list to have the same width
+	if len(queryEmbedding) != len(embeddingList[0]) {
+		return []int{}, errors.New("query embedding width does not match embedding vector width")
+	}
 
-	similarityToQuery, err := CosineSimilarity(queryEmbedding, embeddingList)
+	similarityToQueryMatrix, err := pairwiseCosineSimilarity([][]float32{queryEmbedding}, embeddingList)
 	if err != nil {
 		return nil, err
 	}
-	mostSimilar = floats.MaxIdx(similarityToQuery.RawMatrix().Data)
+	similarityToQuery := similarityToQueryMatrix[0]
+
+	mostSimilar := vek32.ArgMax(similarityToQuery)
 	idxs := []int{mostSimilar}
-	selected := mat.DenseCopyOf(embeddingList.RowView(mostSimilar))
+	selected := [][]float32{embeddingList[mostSimilar]}
 
-	for len(idxs) < min(k, rEmbed) {
-		bestScore = math.Inf(-1)
-		idxToAdd = -1
-		r, c := selected.Dims()
-		selectedTransposed := mat.NewDense(c, r, nil)
-		selectedTransposed.CloneFrom(selected.T())
-		similarityToSelected, err := CosineSimilarity(embeddingList, selectedTransposed)
+	for len(idxs) < min(k, len(embeddingList)) {
+		var bestScore float32 = -math.MaxFloat32
+		idxToAdd := -1
+		similarityToSelected, err := pairwiseCosineSimilarity(embeddingList, selected)
 		if err != nil {
 			return nil, err
 		}
-		for i, queryScore := range similarityToQuery.RawMatrix().Data {
+
+		for i, queryScore := range similarityToQuery {
 			if contains(idxs, i) {
 				continue
 			}
-			redundantScore := floats.Max(similarityToSelected.RawMatrix().Data)
+			redundantScore := vek32.Max(similarityToSelected[i])
 			equationScore := lambdaMult*queryScore - (1-lambdaMult)*redundantScore
 			if equationScore > bestScore {
 				bestScore = equationScore
 				idxToAdd = i
 			}
 		}
 		idxs = append(idxs, idxToAdd)
-		selected.Stack(selected, embeddingList.RowView(idxToAdd))
+		selected = append(selected, embeddingList[idxToAdd])
 	}
 	return idxs, nil
 }
 
+// contains returns true if the slice contains the value
 func contains(slice []int, val int) bool {
 	for _, item := range slice {
 		if item == val {
@@ -123,10 +95,3 @@ func contains(slice []int, val int) bool {
 	}
 	return false
 }
-
-func min(a, b int) int {
-	if a < b {
-		return a
-	}
-	return b
-}