fix: Init analyzer at delegator for all field with enable analyzer (#46361)

To support text match highlight
relate: https://github.com/milvus-io/milvus/issues/46308

Signed-off-by: aoiasd <zhicheng.yue@zilliz.com>

internal/querynodev2/delegator/delegator.go

@@ -1207,6 +1207,17 @@ func NewShardDelegator(ctx context.Context, collectionID UniqueID, replicaID Uni
 		}
 	}
 
+	for _, field := range collection.Schema().GetFields() {
+		helper := typeutil.CreateFieldSchemaHelper(field)
+		if helper.EnableAnalyzer() && sd.analyzerRunners[field.GetFieldID()] == nil {
+			analyzerRunner, err := function.NewAnalyzerRunner(field)
+			if err != nil {
+				return nil, err
+			}
+			sd.analyzerRunners[field.GetFieldID()] = analyzerRunner
+		}
+	}
+
 	if len(sd.isBM25Field) > 0 {
 		sd.idfOracle = NewIDFOracle(sd.vchannelName, collection.Schema().GetFunctions())
 		sd.distribution.SetIDFOracle(sd.idfOracle)

internal/util/function/bm25_function.go

@@ -62,6 +62,20 @@ func getAnalyzerParams(field *schemapb.FieldSchema) string {
 	return "{}"
 }
 
+func NewAnalyzerRunner(field *schemapb.FieldSchema) (Analyzer, error) {
+	params := getAnalyzerParams(field)
+	tokenizer, err := analyzer.NewAnalyzer(params)
+	if err != nil {
+		return nil, err
+	}
+
+	return &BM25FunctionRunner{
+		inputField:  field,
+		tokenizer:   tokenizer,
+		concurrency: 8,
+	}, nil
+}
+
 func NewBM25FunctionRunner(coll *schemapb.CollectionSchema, schema *schemapb.FunctionSchema) (FunctionRunner, error) {
 	if len(schema.GetOutputFieldIds()) != 1 {
 		return nil, fmt.Errorf("bm25 function should only have one output field, but now %d", len(schema.GetOutputFieldIds()))