Fix offset panic (#21292) (#21751)

Signed-off-by: lixinguo <xinguo.li@zilliz.com>
Co-authored-by: lixinguo <xinguo.li@zilliz.com>

internal/proxy/task_query.go

@@ -394,6 +394,13 @@ func (t *queryTask) PostExecute(ctx context.Context) error {
 		}
 		for _, field := range schema.Fields {
 			if field.FieldID == t.OutputFieldsId[i] {
+				// deal with the situation that offset equal to or greater than the number of entities
+				if t.result.FieldsData[i] == nil {
+					t.result.FieldsData[i], err = typeutil.GenEmptyFieldData(field)
+					if err != nil {
+						return err
+					}
+				}
 				t.result.FieldsData[i].FieldName = field.Name
 				t.result.FieldsData[i].FieldId = field.FieldID
 				t.result.FieldsData[i].Type = field.DataType

internal/proxy/task_query_test.go

@@ -200,6 +200,10 @@ func TestQueryTask_all(t *testing.T) {
 
 	assert.NoError(t, task.Execute(ctx))
 
+	task.queryParams = &queryParams{
+		limit:  100,
+		offset: 100,
+	}
 	assert.NoError(t, task.PostExecute(ctx))
 
 	for i := 0; i < len(task.result.FieldsData); i++ {

internal/util/typeutil/gen_empty_field_data.go

@@ -140,7 +140,7 @@ func genEmptyFloatVectorFieldData(field *schemapb.FieldSchema) (*schemapb.FieldD
 	}, nil
 }
 
-func genEmptyFieldData(field *schemapb.FieldSchema) (*schemapb.FieldData, error) {
+func GenEmptyFieldData(field *schemapb.FieldSchema) (*schemapb.FieldData, error) {
 	dataType := field.GetDataType()
 	switch dataType {
 	case schemapb.DataType_Bool:

internal/util/typeutil/result_helper.go

@@ -29,7 +29,7 @@ func FillRetrieveResultIfEmpty(result RetrieveResults, outputFieldIds []int64, s
 			return err
 		}
 
-		emptyFieldData, err := genEmptyFieldData(field)
+		emptyFieldData, err := GenEmptyFieldData(field)
 		if err != nil {
 			return err
 		}

internal/util/typeutil/result_helper_test.go

@@ -39,7 +39,7 @@ func TestGenEmptyFieldData(t *testing.T) {
 	field := &schemapb.FieldSchema{Name: "field_name", FieldID: 100}
 	for _, dataType := range allTypes {
 		field.DataType = dataType
-		fieldData, err := genEmptyFieldData(field)
+		fieldData, err := GenEmptyFieldData(field)
 		assert.NoError(t, err)
 		assert.Equal(t, dataType, fieldData.GetType())
 		assert.Equal(t, field.GetName(), fieldData.GetFieldName())
@@ -49,21 +49,21 @@ func TestGenEmptyFieldData(t *testing.T) {
 
 	for _, dataType := range allUnsupportedTypes {
 		field.DataType = dataType
-		_, err := genEmptyFieldData(field)
+		_, err := GenEmptyFieldData(field)
 		assert.Error(t, err)
 	}
 
 	// dim not found
 	for _, dataType := range vectorTypes {
 		field.DataType = dataType
-		_, err := genEmptyFieldData(field)
+		_, err := GenEmptyFieldData(field)
 		assert.Error(t, err)
 	}
 
 	field.TypeParams = []*commonpb.KeyValuePair{{Key: "dim", Value: "128"}}
 	for _, dataType := range vectorTypes {
 		field.DataType = dataType
-		fieldData, err := genEmptyFieldData(field)
+		fieldData, err := GenEmptyFieldData(field)
 		assert.NoError(t, err)
 		assert.Equal(t, dataType, fieldData.GetType())
 		assert.Equal(t, field.GetName(), fieldData.GetFieldName())