fix: fixing ngram index rejecting mmap (#44175)

issue: https://github.com/milvus-io/milvus/issues/44164

Signed-off-by: SpadeA <tangchenjie1210@gmail.com>

internal/util/indexparamcheck/index_type.go

@@ -64,7 +64,8 @@ func IsScalarMmapIndex(indexType IndexType) bool {
 	return indexType == IndexINVERTED ||
 		indexType == IndexBitmap ||
 		indexType == IndexHybrid ||
-		indexType == IndexTrie
+		indexType == IndexTrie ||
+		indexType == IndexNGRAM
 }
 
 func ValidateMmapIndexParams(indexType IndexType, indexParams map[string]string) error {

internal/util/indexparamcheck/index_type_test.go

@@ -65,4 +65,11 @@ func TestValidateMmapTypeParams(t *testing.T) {
 		})
 		assert.Error(t, err)
 	})
+
+	t.Run("stl_mmap mmap enable", func(t *testing.T) {
+		err := ValidateMmapIndexParams(IndexNGRAM, map[string]string{
+			common.MmapEnabledKey: "true",
+		})
+		assert.NoError(t, err)
+	})
 }