[FIX] Set max fuzziness to 2 for bleve (#3444)

closes #3443

regression from ab5f0b7558

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/3444
Reviewed-by: Otto <otto@codeberg.org>
Co-authored-by: Shiny Nematoda <snematoda.751k2@aleeas.com>
Co-committed-by: Shiny Nematoda <snematoda.751k2@aleeas.com>
(cherry picked from commit a641ebf221)

modules/indexer/code/bleve/bleve.go

@@ -41,6 +41,8 @@ const (
 	maxBatchSize         = 16
 	// fuzzyDenominator determines the levenshtein distance per each character of a keyword
 	fuzzyDenominator = 4
+	// see https://github.com/blevesearch/bleve/issues/1563#issuecomment-786822311
+	maxFuzziness = 2
 )
 
 func addUnicodeNormalizeTokenFilter(m *mapping.IndexMappingImpl) error {
@@ -246,7 +248,7 @@ func (b *Indexer) Search(ctx context.Context, opts *internal.SearchOptions) (int
 	phraseQuery.Analyzer = repoIndexerAnalyzer
 	keywordQuery = phraseQuery
 	if opts.IsKeywordFuzzy {
-		phraseQuery.Fuzziness = len(opts.Keyword) / fuzzyDenominator
+		phraseQuery.Fuzziness = min(maxFuzziness, len(opts.Keyword)/fuzzyDenominator)
 	}
 
 	if len(opts.RepoIDs) > 0 {

modules/indexer/code/indexer_test.go

@@ -49,6 +49,12 @@ func testIndexer(name string, t *testing.T, indexer internal.Indexer) {
 				IDs:     []int64{},
 				Langs:   0,
 			},
+			{
+				RepoIDs: nil,
+				Keyword: "Description for",
+				IDs:     []int64{repoID},
+				Langs:   1,
+			},
 			{
 				RepoIDs: nil,
 				Keyword: "repo1",

modules/indexer/issues/bleve/bleve.go

@@ -39,6 +39,8 @@ const (
 	maxBatchSize = 16
 	// fuzzyDenominator determines the levenshtein distance per each character of a keyword
 	fuzzyDenominator = 4
+	// see https://github.com/blevesearch/bleve/issues/1563#issuecomment-786822311
+	maxFuzziness = 2
 )
 
 // IndexerData an update to the issue indexer
@@ -162,7 +164,7 @@ func (b *Indexer) Search(ctx context.Context, options *internal.SearchOptions) (
 	if options.Keyword != "" {
 		fuzziness := 0
 		if options.IsFuzzyKeyword {
-			fuzziness = len(options.Keyword) / fuzzyDenominator
+			fuzziness = min(maxFuzziness, len(options.Keyword)/fuzzyDenominator)
 		}
 
 		queries = append(queries, bleve.NewDisjunctionQuery([]query.Query{

modules/indexer/issues/internal/tests/tests.go

@@ -130,6 +130,20 @@ var cases = []*testIndexerCase{
 		ExpectedIDs:   []int64{1002, 1001, 1000},
 		ExpectedTotal: 3,
 	},
+	{
+		Name: "Keyword Fuzzy",
+		ExtraData: []*internal.IndexerData{
+			{ID: 1000, Title: "hi hello world"},
+			{ID: 1001, Content: "hi hello world"},
+			{ID: 1002, Comments: []string{"hi", "hello world"}},
+		},
+		SearchOptions: &internal.SearchOptions{
+			Keyword:        "hello wrold",
+			IsFuzzyKeyword: true,
+		},
+		ExpectedIDs:   []int64{1002, 1001, 1000},
+		ExpectedTotal: 3,
+	},
 	{
 		Name: "RepoIDs",
 		ExtraData: []*internal.IndexerData{