Improve issue & code search (#33860)

Each "indexer" should provide the "search modes" they support by
themselves. And we need to remove the "fuzzy" search for code.

modules/indexer/code/bleve/bleve.go

@@ -17,6 +17,7 @@ import (
 	"code.gitea.io/gitea/modules/charset"
 	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/gitrepo"
+	"code.gitea.io/gitea/modules/indexer"
 	path_filter "code.gitea.io/gitea/modules/indexer/code/bleve/token/path"
 	"code.gitea.io/gitea/modules/indexer/code/internal"
 	indexer_internal "code.gitea.io/gitea/modules/indexer/internal"
@@ -136,6 +137,10 @@ type Indexer struct {
 	indexer_internal.Indexer // do not composite inner_bleve.Indexer directly to avoid exposing too much
 }
 
+func (b *Indexer) SupportedSearchModes() []indexer.SearchMode {
+	return indexer.SearchModesExactWords()
+}
+
 // NewIndexer creates a new bleve local indexer
 func NewIndexer(indexDir string) *Indexer {
 	inner := inner_bleve.NewIndexer(indexDir, repoIndexerLatestVersion, generateBleveIndexMapping)
@@ -267,19 +272,18 @@ func (b *Indexer) Search(ctx context.Context, opts *internal.SearchOptions) (int
 	pathQuery.FieldVal = "Filename"
 	pathQuery.SetBoost(10)
 
-	keywordAsPhrase, isPhrase := internal.ParseKeywordAsPhrase(opts.Keyword)
-	if isPhrase {
-		q := bleve.NewMatchPhraseQuery(keywordAsPhrase)
+	if opts.SearchMode == indexer.SearchModeExact {
+		q := bleve.NewMatchPhraseQuery(opts.Keyword)
 		q.FieldVal = "Content"
-		if opts.IsKeywordFuzzy {
-			q.Fuzziness = inner_bleve.GuessFuzzinessByKeyword(keywordAsPhrase)
-		}
 		contentQuery = q
-	} else {
+	} else /* words */ {
 		q := bleve.NewMatchQuery(opts.Keyword)
 		q.FieldVal = "Content"
-		if opts.IsKeywordFuzzy {
+		if opts.SearchMode == indexer.SearchModeFuzzy {
+			// this logic doesn't seem right, it is only used to pass the test-case `Keyword:    "dESCRIPTION"`, which doesn't seem to be a real-life use-case.
 			q.Fuzziness = inner_bleve.GuessFuzzinessByKeyword(opts.Keyword)
+		} else {
+			q.Operator = query.MatchQueryOperatorAnd
 		}
 		contentQuery = q
 	}

modules/indexer/code/elasticsearch/elasticsearch.go

@@ -16,6 +16,7 @@ import (
 	"code.gitea.io/gitea/modules/charset"
 	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/gitrepo"
+	"code.gitea.io/gitea/modules/indexer"
 	"code.gitea.io/gitea/modules/indexer/code/internal"
 	indexer_internal "code.gitea.io/gitea/modules/indexer/internal"
 	inner_elasticsearch "code.gitea.io/gitea/modules/indexer/internal/elasticsearch"
@@ -24,7 +25,6 @@ import (
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/timeutil"
 	"code.gitea.io/gitea/modules/typesniffer"
-	"code.gitea.io/gitea/modules/util"
 
 	"github.com/go-enry/go-enry/v2"
 	"github.com/olivere/elastic/v7"
@@ -46,6 +46,10 @@ type Indexer struct {
 	indexer_internal.Indexer // do not composite inner_elasticsearch.Indexer directly to avoid exposing too much
 }
 
+func (b *Indexer) SupportedSearchModes() []indexer.SearchMode {
+	return indexer.SearchModesExactWords()
+}
+
 // NewIndexer creates a new elasticsearch indexer
 func NewIndexer(url, indexerName string) *Indexer {
 	inner := inner_elasticsearch.NewIndexer(url, indexerName, esRepoIndexerLatestVersion, defaultMapping)
@@ -361,15 +365,10 @@ func extractAggs(searchResult *elastic.SearchResult) []*internal.SearchResultLan
 // Search searches for codes and language stats by given conditions.
 func (b *Indexer) Search(ctx context.Context, opts *internal.SearchOptions) (int64, []*internal.SearchResult, []*internal.SearchResultLanguages, error) {
 	var contentQuery elastic.Query
-	keywordAsPhrase, isPhrase := internal.ParseKeywordAsPhrase(opts.Keyword)
-	if isPhrase {
-		contentQuery = elastic.NewMatchPhraseQuery("content", keywordAsPhrase)
-	} else {
-		// TODO: this is the old logic, but not really using "fuzziness"
-		// * IsKeywordFuzzy=true: "best_fields"
-		// * IsKeywordFuzzy=false: "phrase_prefix"
-		contentQuery = elastic.NewMultiMatchQuery("content", opts.Keyword).
-			Type(util.Iif(opts.IsKeywordFuzzy, esMultiMatchTypeBestFields, esMultiMatchTypePhrasePrefix))
+	if opts.SearchMode == indexer.SearchModeExact {
+		contentQuery = elastic.NewMatchPhraseQuery("content", opts.Keyword)
+	} else /* words */ {
+		contentQuery = elastic.NewMultiMatchQuery("content", opts.Keyword).Type(esMultiMatchTypeBestFields).Operator("and")
 	}
 	kwQuery := elastic.NewBoolQuery().Should(
 		contentQuery,

modules/indexer/code/gitgrep/gitgrep.go

@@ -9,6 +9,7 @@ import (
 	"strings"
 
 	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/indexer"
 	code_indexer "code.gitea.io/gitea/modules/indexer/code"
 	"code.gitea.io/gitea/modules/setting"
 )
@@ -23,11 +24,16 @@ func indexSettingToGitGrepPathspecList() (list []string) {
 	return list
 }
 
-func PerformSearch(ctx context.Context, page int, repoID int64, gitRepo *git.Repository, ref git.RefName, keyword string, isFuzzy bool) (searchResults []*code_indexer.Result, total int, err error) {
-	// TODO: it should also respect ParseKeywordAsPhrase and clarify the "fuzzy" behavior
+func PerformSearch(ctx context.Context, page int, repoID int64, gitRepo *git.Repository, ref git.RefName, keyword string, searchMode indexer.SearchModeType) (searchResults []*code_indexer.Result, total int, err error) {
+	grepMode := git.GrepModeWords
+	if searchMode == indexer.SearchModeExact {
+		grepMode = git.GrepModeExact
+	} else if searchMode == indexer.SearchModeRegexp {
+		grepMode = git.GrepModeRegexp
+	}
 	res, err := git.GrepSearch(ctx, gitRepo, keyword, git.GrepOptions{
 		ContextLineNumber: 1,
-		IsFuzzy:           isFuzzy,
+		GrepMode:          grepMode,
 		RefName:           ref.String(),
 		PathspecList:      indexSettingToGitGrepPathspecList(),
 	})

modules/indexer/code/indexer.go

@@ -14,6 +14,7 @@ import (
 	"code.gitea.io/gitea/models/db"
 	repo_model "code.gitea.io/gitea/models/repo"
 	"code.gitea.io/gitea/modules/graceful"
+	"code.gitea.io/gitea/modules/indexer"
 	"code.gitea.io/gitea/modules/indexer/code/bleve"
 	"code.gitea.io/gitea/modules/indexer/code/elasticsearch"
 	"code.gitea.io/gitea/modules/indexer/code/internal"
@@ -302,3 +303,11 @@ func populateRepoIndexer(ctx context.Context) {
 	}
 	log.Info("Done (re)populating the repo indexer with existing repositories")
 }
+
+func SupportedSearchModes() []indexer.SearchMode {
+	gi := globalIndexer.Load()
+	if gi == nil {
+		return nil
+	}
+	return (*gi).SupportedSearchModes()
+}

modules/indexer/code/indexer_test.go

@@ -11,6 +11,7 @@ import (
 
 	"code.gitea.io/gitea/models/db"
 	"code.gitea.io/gitea/models/unittest"
+	indexer_module "code.gitea.io/gitea/modules/indexer"
 	"code.gitea.io/gitea/modules/indexer/code/bleve"
 	"code.gitea.io/gitea/modules/indexer/code/elasticsearch"
 	"code.gitea.io/gitea/modules/indexer/code/internal"
@@ -39,10 +40,11 @@ func testIndexer(name string, t *testing.T, indexer internal.Indexer) {
 		assert.NoError(t, setupRepositoryIndexes(t.Context(), indexer))
 
 		keywords := []struct {
-			RepoIDs []int64
-			Keyword string
-			Langs   int
-			Results []codeSearchResult
+			RepoIDs    []int64
+			Keyword    string
+			Langs      int
+			SearchMode indexer_module.SearchModeType
+			Results    []codeSearchResult
 		}{
 			// Search for an exact match on the contents of a file
 			// This scenario yields a single result (the file README.md on the repo '1')
@@ -183,9 +185,10 @@ func testIndexer(name string, t *testing.T, indexer internal.Indexer) {
 			},
 			// Search for matches on the contents of files regardless of case.
 			{
-				RepoIDs: nil,
-				Keyword: "dESCRIPTION",
-				Langs:   1,
+				RepoIDs:    nil,
+				Keyword:    "dESCRIPTION",
+				Langs:      1,
+				SearchMode: indexer_module.SearchModeFuzzy,
 				Results: []codeSearchResult{
 					{
 						Filename: "README.md",
@@ -193,7 +196,7 @@ func testIndexer(name string, t *testing.T, indexer internal.Indexer) {
 					},
 				},
 			},
-			// Search for an exact match on the filename within the repo '62' (case insenstive).
+			// Search for an exact match on the filename within the repo '62' (case-insensitive).
 			// This scenario yields a single result (the file avocado.md on the repo '62')
 			{
 				RepoIDs: []int64{62},
@@ -206,7 +209,7 @@ func testIndexer(name string, t *testing.T, indexer internal.Indexer) {
 					},
 				},
 			},
-			// Search for matches on the contents of files when the criteria is a expression.
+			// Search for matches on the contents of files when the criteria are an expression.
 			{
 				RepoIDs: []int64{62},
 				Keyword: "console.log",
@@ -218,7 +221,7 @@ func testIndexer(name string, t *testing.T, indexer internal.Indexer) {
 					},
 				},
 			},
-			// Search for matches on the contents of files when the criteria is part of a expression.
+			// Search for matches on the contents of files when the criteria are parts of an expression.
 			{
 				RepoIDs: []int64{62},
 				Keyword: "log",
@@ -235,16 +238,16 @@ func testIndexer(name string, t *testing.T, indexer internal.Indexer) {
 		for _, kw := range keywords {
 			t.Run(kw.Keyword, func(t *testing.T) {
 				total, res, langs, err := indexer.Search(t.Context(), &internal.SearchOptions{
-					RepoIDs: kw.RepoIDs,
-					Keyword: kw.Keyword,
+					RepoIDs:    kw.RepoIDs,
+					Keyword:    kw.Keyword,
+					SearchMode: kw.SearchMode,
 					Paginator: &db.ListOptions{
 						Page:     1,
 						PageSize: 10,
 					},
-					IsKeywordFuzzy: true,
 				})
-				assert.NoError(t, err)
-				assert.Len(t, langs, kw.Langs)
+				require.NoError(t, err)
+				require.Len(t, langs, kw.Langs)
 
 				hits := make([]codeSearchResult, 0, len(res))
 
@@ -289,7 +292,7 @@ func TestBleveIndexAndSearch(t *testing.T) {
 	_, err := idx.Init(t.Context())
 	require.NoError(t, err)
 
-	testIndexer("beleve", t, idx)
+	testIndexer("bleve", t, idx)
 }
 
 func TestESIndexAndSearch(t *testing.T) {

modules/indexer/code/internal/indexer.go

@@ -9,6 +9,7 @@ import (
 
 	"code.gitea.io/gitea/models/db"
 	repo_model "code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/modules/indexer"
 	"code.gitea.io/gitea/modules/indexer/internal"
 )
 
@@ -18,6 +19,7 @@ type Indexer interface {
 	Index(ctx context.Context, repo *repo_model.Repository, sha string, changes *RepoChanges) error
 	Delete(ctx context.Context, repoID int64) error
 	Search(ctx context.Context, opts *SearchOptions) (int64, []*SearchResult, []*SearchResultLanguages, error)
+	SupportedSearchModes() []indexer.SearchMode
 }
 
 type SearchOptions struct {
@@ -25,7 +27,7 @@ type SearchOptions struct {
 	Keyword  string
 	Language string
 
-	IsKeywordFuzzy bool
+	SearchMode indexer.SearchModeType
 
 	db.Paginator
 }
@@ -41,6 +43,10 @@ type dummyIndexer struct {
 	internal.Indexer
 }
 
+func (d *dummyIndexer) SupportedSearchModes() []indexer.SearchMode {
+	return nil
+}
+
 func (d *dummyIndexer) Index(ctx context.Context, repo *repo_model.Repository, sha string, changes *RepoChanges) error {
 	return fmt.Errorf("indexer is not ready")
 }

modules/indexer/code/internal/util.go

@@ -10,9 +10,7 @@ import (
 	"code.gitea.io/gitea/modules/log"
 )
 
-const (
-	filenameMatchNumberOfLines = 7 // Copied from github search
-)
+const filenameMatchNumberOfLines = 7 // Copied from GitHub search
 
 func FilenameIndexerID(repoID int64, filename string) string {
 	return internal.Base36(repoID) + "_" + filename
@@ -48,11 +46,3 @@ func FilenameMatchIndexPos(content string) (int, int) {
 	}
 	return 0, len(content)
 }
-
-func ParseKeywordAsPhrase(keyword string) (string, bool) {
-	if strings.HasPrefix(keyword, `"`) && strings.HasSuffix(keyword, `"`) && len(keyword) > 1 {
-		// only remove the prefix and suffix quotes, no need to decode the content at the moment
-		return keyword[1 : len(keyword)-1], true
-	}
-	return "", false
-}

modules/indexer/code/internal/util_test.go

@@ -1,30 +0,0 @@
-// Copyright 2025 The Gitea Authors. All rights reserved.
-// SPDX-License-Identifier: MIT
-
-package internal
-
-import (
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-)
-
-func TestParseKeywordAsPhrase(t *testing.T) {
-	cases := []struct {
-		keyword  string
-		phrase   string
-		isPhrase bool
-	}{
-		{``, "", false},
-		{`a`, "", false},
-		{`"`, "", false},
-		{`"a`, "", false},
-		{`"a"`, "a", true},
-		{`""\"""`, `"\""`, true},
-	}
-	for _, c := range cases {
-		phrase, isPhrase := ParseKeywordAsPhrase(c.keyword)
-		assert.Equal(t, c.phrase, phrase, "keyword=%q", c.keyword)
-		assert.Equal(t, c.isPhrase, isPhrase, "keyword=%q", c.keyword)
-	}
-}

modules/indexer/code/search.go

@@ -129,7 +129,6 @@ func searchResult(result *internal.SearchResult, startIndex, endIndex int) (*Res
 }
 
 // PerformSearch perform a search on a repository
-// if isFuzzy is true set the Damerau-Levenshtein distance from 0 to 2
 func PerformSearch(ctx context.Context, opts *SearchOptions) (int, []*Result, []*SearchResultLanguages, error) {
 	if opts == nil || len(opts.Keyword) == 0 {
 		return 0, nil, nil, nil

modules/indexer/indexer.go

@@ -0,0 +1,54 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package indexer
+
+type SearchModeType string
+
+const (
+	SearchModeExact  SearchModeType = "exact"
+	SearchModeWords  SearchModeType = "words"
+	SearchModeFuzzy  SearchModeType = "fuzzy"
+	SearchModeRegexp SearchModeType = "regexp"
+)
+
+type SearchMode struct {
+	ModeValue    SearchModeType
+	TooltipTrKey string
+	TitleTrKey   string
+}
+
+func SearchModesExactWords() []SearchMode {
+	return []SearchMode{
+		{
+			ModeValue:    SearchModeExact,
+			TooltipTrKey: "search.exact_tooltip",
+			TitleTrKey:   "search.exact",
+		},
+		{
+			ModeValue:    SearchModeWords,
+			TooltipTrKey: "search.words_tooltip",
+			TitleTrKey:   "search.words",
+		},
+	}
+}
+
+func SearchModesExactWordsFuzzy() []SearchMode {
+	return append(SearchModesExactWords(), []SearchMode{
+		{
+			ModeValue:    SearchModeFuzzy,
+			TooltipTrKey: "search.fuzzy_tooltip",
+			TitleTrKey:   "search.fuzzy",
+		},
+	}...)
+}
+
+func GitGrepSupportedSearchModes() []SearchMode {
+	return append(SearchModesExactWords(), []SearchMode{
+		{
+			ModeValue:    SearchModeRegexp,
+			TooltipTrKey: "search.regexp_tooltip",
+			TitleTrKey:   "search.regexp",
+		},
+	}...)
+}

modules/indexer/internal/bleve/query.go

@@ -28,6 +28,16 @@ func MatchPhraseQuery(matchPhrase, field, analyzer string, fuzziness int) *query
 	return q
 }
 
+// MatchAndQuery generates a match query for the given phrase, field and analyzer
+func MatchAndQuery(matchPhrase, field, analyzer string, fuzziness int) *query.MatchQuery {
+	q := bleve.NewMatchQuery(matchPhrase)
+	q.FieldVal = field
+	q.Analyzer = analyzer
+	q.Fuzziness = fuzziness
+	q.Operator = query.MatchQueryOperatorAnd
+	return q
+}
+
 // BoolFieldQuery generates a bool field query for the given value and field
 func BoolFieldQuery(value bool, field string) *query.BoolFieldQuery {
 	q := bleve.NewBoolFieldQuery(value)

modules/indexer/issues/bleve/bleve.go

@@ -6,6 +6,7 @@ package bleve
 import (
 	"context"
 
+	"code.gitea.io/gitea/modules/indexer"
 	indexer_internal "code.gitea.io/gitea/modules/indexer/internal"
 	inner_bleve "code.gitea.io/gitea/modules/indexer/internal/bleve"
 	"code.gitea.io/gitea/modules/indexer/issues/internal"
@@ -120,6 +121,10 @@ type Indexer struct {
 	indexer_internal.Indexer // do not composite inner_bleve.Indexer directly to avoid exposing too much
 }
 
+func (b *Indexer) SupportedSearchModes() []indexer.SearchMode {
+	return indexer.SearchModesExactWordsFuzzy()
+}
+
 // NewIndexer creates a new bleve local indexer
 func NewIndexer(indexDir string) *Indexer {
 	inner := inner_bleve.NewIndexer(indexDir, issueIndexerLatestVersion, generateIssueIndexMapping)
@@ -157,16 +162,23 @@ func (b *Indexer) Search(ctx context.Context, options *internal.SearchOptions) (
 	var queries []query.Query
 
 	if options.Keyword != "" {
-		fuzziness := 0
-		if options.IsFuzzyKeyword {
-			fuzziness = inner_bleve.GuessFuzzinessByKeyword(options.Keyword)
+		if options.SearchMode == indexer.SearchModeWords || options.SearchMode == indexer.SearchModeFuzzy {
+			fuzziness := 0
+			if options.SearchMode == indexer.SearchModeFuzzy {
+				fuzziness = inner_bleve.GuessFuzzinessByKeyword(options.Keyword)
+			}
+			queries = append(queries, bleve.NewDisjunctionQuery([]query.Query{
+				inner_bleve.MatchAndQuery(options.Keyword, "title", issueIndexerAnalyzer, fuzziness),
+				inner_bleve.MatchAndQuery(options.Keyword, "content", issueIndexerAnalyzer, fuzziness),
+				inner_bleve.MatchAndQuery(options.Keyword, "comments", issueIndexerAnalyzer, fuzziness),
+			}...))
+		} else /* exact */ {
+			queries = append(queries, bleve.NewDisjunctionQuery([]query.Query{
+				inner_bleve.MatchPhraseQuery(options.Keyword, "title", issueIndexerAnalyzer, 0),
+				inner_bleve.MatchPhraseQuery(options.Keyword, "content", issueIndexerAnalyzer, 0),
+				inner_bleve.MatchPhraseQuery(options.Keyword, "comments", issueIndexerAnalyzer, 0),
+			}...))
 		}
-
-		queries = append(queries, bleve.NewDisjunctionQuery([]query.Query{
-			inner_bleve.MatchPhraseQuery(options.Keyword, "title", issueIndexerAnalyzer, fuzziness),
-			inner_bleve.MatchPhraseQuery(options.Keyword, "content", issueIndexerAnalyzer, fuzziness),
-			inner_bleve.MatchPhraseQuery(options.Keyword, "comments", issueIndexerAnalyzer, fuzziness),
-		}...))
 	}
 
 	if len(options.RepoIDs) > 0 || options.AllPublic {

modules/indexer/issues/db/db.go

@@ -5,9 +5,11 @@ package db
 
 import (
 	"context"
+	"strings"
 
 	"code.gitea.io/gitea/models/db"
 	issue_model "code.gitea.io/gitea/models/issues"
+	"code.gitea.io/gitea/modules/indexer"
 	indexer_internal "code.gitea.io/gitea/modules/indexer/internal"
 	inner_db "code.gitea.io/gitea/modules/indexer/internal/db"
 	"code.gitea.io/gitea/modules/indexer/issues/internal"
@@ -22,6 +24,10 @@ type Indexer struct {
 	indexer_internal.Indexer
 }
 
+func (i *Indexer) SupportedSearchModes() []indexer.SearchMode {
+	return indexer.SearchModesExactWords()
+}
+
 func NewIndexer() *Indexer {
 	return &Indexer{
 		Indexer: &inner_db.Indexer{},
@@ -38,6 +44,26 @@ func (i *Indexer) Delete(_ context.Context, _ ...int64) error {
 	return nil
 }
 
+func buildMatchQuery(mode indexer.SearchModeType, colName, keyword string) builder.Cond {
+	if mode == indexer.SearchModeExact {
+		return db.BuildCaseInsensitiveLike("issue.name", keyword)
+	}
+
+	// match words
+	cond := builder.NewCond()
+	fields := strings.Fields(keyword)
+	if len(fields) == 0 {
+		return builder.Expr("1=1")
+	}
+	for _, field := range fields {
+		if field == "" {
+			continue
+		}
+		cond = cond.And(db.BuildCaseInsensitiveLike(colName, field))
+	}
+	return cond
+}
+
 // Search searches for issues
 func (i *Indexer) Search(ctx context.Context, options *internal.SearchOptions) (*internal.SearchResult, error) {
 	// FIXME: I tried to avoid importing models here, but it seems to be impossible.
@@ -60,14 +86,14 @@ func (i *Indexer) Search(ctx context.Context, options *internal.SearchOptions) (
 		subQuery := builder.Select("id").From("issue").Where(repoCond)
 
 		cond = builder.Or(
-			db.BuildCaseInsensitiveLike("issue.name", options.Keyword),
-			db.BuildCaseInsensitiveLike("issue.content", options.Keyword),
+			buildMatchQuery(options.SearchMode, "issue.name", options.Keyword),
+			buildMatchQuery(options.SearchMode, "issue.content", options.Keyword),
 			builder.In("issue.id", builder.Select("issue_id").
 				From("comment").
 				Where(builder.And(
 					builder.Eq{"type": issue_model.CommentTypeComment},
 					builder.In("issue_id", subQuery),
-					db.BuildCaseInsensitiveLike("content", options.Keyword),
+					buildMatchQuery(options.SearchMode, "content", options.Keyword),
 				)),
 			),
 		)

modules/indexer/issues/elasticsearch/elasticsearch.go

@@ -10,6 +10,7 @@ import (
 	"strings"
 
 	"code.gitea.io/gitea/modules/graceful"
+	"code.gitea.io/gitea/modules/indexer"
 	indexer_internal "code.gitea.io/gitea/modules/indexer/internal"
 	inner_elasticsearch "code.gitea.io/gitea/modules/indexer/internal/elasticsearch"
 	"code.gitea.io/gitea/modules/indexer/issues/internal"
@@ -33,6 +34,11 @@ type Indexer struct {
 	indexer_internal.Indexer // do not composite inner_elasticsearch.Indexer directly to avoid exposing too much
 }
 
+func (b *Indexer) SupportedSearchModes() []indexer.SearchMode {
+	// TODO: es supports fuzzy search, but our code doesn't at the moment, and actually the default fuzziness is already "AUTO"
+	return indexer.SearchModesExactWords()
+}
+
 // NewIndexer creates a new elasticsearch indexer
 func NewIndexer(url, indexerName string) *Indexer {
 	inner := inner_elasticsearch.NewIndexer(url, indexerName, issueIndexerLatestVersion, defaultMapping)
@@ -146,12 +152,11 @@ func (b *Indexer) Search(ctx context.Context, options *internal.SearchOptions) (
 	query := elastic.NewBoolQuery()
 
 	if options.Keyword != "" {
-		searchType := esMultiMatchTypePhrasePrefix
-		if options.IsFuzzyKeyword {
-			searchType = esMultiMatchTypeBestFields
+		if options.SearchMode == indexer.SearchModeExact {
+			query.Must(elastic.NewMultiMatchQuery(options.Keyword, "title", "content", "comments").Type(esMultiMatchTypePhrasePrefix))
+		} else /* words */ {
+			query.Must(elastic.NewMultiMatchQuery(options.Keyword, "title", "content", "comments").Type(esMultiMatchTypeBestFields).Operator("and"))
 		}
-
-		query.Must(elastic.NewMultiMatchQuery(options.Keyword, "title", "content", "comments").Type(searchType))
 	}
 
 	if len(options.RepoIDs) > 0 {

modules/indexer/issues/indexer.go

@@ -14,6 +14,7 @@ import (
 	db_model "code.gitea.io/gitea/models/db"
 	repo_model "code.gitea.io/gitea/models/repo"
 	"code.gitea.io/gitea/modules/graceful"
+	"code.gitea.io/gitea/modules/indexer"
 	"code.gitea.io/gitea/modules/indexer/issues/bleve"
 	"code.gitea.io/gitea/modules/indexer/issues/db"
 	"code.gitea.io/gitea/modules/indexer/issues/elasticsearch"
@@ -313,3 +314,11 @@ func CountIssues(ctx context.Context, opts *SearchOptions) (int64, error) {
 	_, total, err := SearchIssues(ctx, opts)
 	return total, err
 }
+
+func SupportedSearchModes() []indexer.SearchMode {
+	gi := globalIndexer.Load()
+	if gi == nil {
+		return nil
+	}
+	return (*gi).SupportedSearchModes()
+}

modules/indexer/issues/internal/indexer.go

@@ -7,6 +7,7 @@ import (
 	"context"
 	"fmt"
 
+	"code.gitea.io/gitea/modules/indexer"
 	"code.gitea.io/gitea/modules/indexer/internal"
 )
 
@@ -16,6 +17,7 @@ type Indexer interface {
 	Index(ctx context.Context, issue ...*IndexerData) error
 	Delete(ctx context.Context, ids ...int64) error
 	Search(ctx context.Context, options *SearchOptions) (*SearchResult, error)
+	SupportedSearchModes() []indexer.SearchMode
 }
 
 // NewDummyIndexer returns a dummy indexer
@@ -29,6 +31,10 @@ type dummyIndexer struct {
 	internal.Indexer
 }
 
+func (d *dummyIndexer) SupportedSearchModes() []indexer.SearchMode {
+	return nil
+}
+
 func (d *dummyIndexer) Index(_ context.Context, _ ...*IndexerData) error {
 	return fmt.Errorf("indexer is not ready")
 }

modules/indexer/issues/internal/model.go

@@ -7,6 +7,7 @@ import (
 	"strconv"
 
 	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/modules/indexer"
 	"code.gitea.io/gitea/modules/optional"
 	"code.gitea.io/gitea/modules/timeutil"
 )
@@ -77,7 +78,7 @@ type SearchResult struct {
 type SearchOptions struct {
 	Keyword string // keyword to search
 
-	IsFuzzyKeyword bool // if false the levenshtein distance is 0
+	SearchMode indexer.SearchModeType
 
 	RepoIDs   []int64 // repository IDs which the issues belong to
 	AllPublic bool    // if include all public repositories

modules/indexer/issues/meilisearch/meilisearch.go

@@ -10,6 +10,7 @@ import (
 	"strconv"
 	"strings"
 
+	"code.gitea.io/gitea/modules/indexer"
 	indexer_internal "code.gitea.io/gitea/modules/indexer/internal"
 	inner_meilisearch "code.gitea.io/gitea/modules/indexer/internal/meilisearch"
 	"code.gitea.io/gitea/modules/indexer/issues/internal"
@@ -35,6 +36,10 @@ type Indexer struct {
 	indexer_internal.Indexer // do not composite inner_meilisearch.Indexer directly to avoid exposing too much
 }
 
+func (b *Indexer) SupportedSearchModes() []indexer.SearchMode {
+	return indexer.SearchModesExactWords()
+}
+
 // NewIndexer creates a new meilisearch indexer
 func NewIndexer(url, apiKey, indexerName string) *Indexer {
 	settings := &meilisearch.Settings{
@@ -230,9 +235,8 @@ func (b *Indexer) Search(ctx context.Context, options *internal.SearchOptions) (
 		limit = 1
 	}
 
-	keyword := options.Keyword
-	if !options.IsFuzzyKeyword {
-		// to make it non fuzzy ("typo tolerance" in meilisearch terms), we have to quote the keyword(s)
+	keyword := options.Keyword // default to match "words"
+	if options.SearchMode == indexer.SearchModeExact {
 		// https://www.meilisearch.com/docs/reference/api/search#phrase-search
 		keyword = doubleQuoteKeyword(keyword)
 	}