diff --git a/src/tsdb/src/tsdbRead.c b/src/tsdb/src/tsdbRead.c
index 1e230dad490d27223078bfb6c6347e17d5763b0e..8e11e445673b70d2257ef14178fa05225260f36f 100644
--- a/src/tsdb/src/tsdbRead.c
+++ b/src/tsdb/src/tsdbRead.c
@@ -4088,8 +4088,8 @@ static FORCE_INLINE int32_t tsdbGetJsonTagDataFromId(void *param, int32_t id, ch
     *data = TABLE_NAME(pTable);
   } else {
     void* jsonData = getJsonTagValue(pTable, name, TSDB_MAX_JSON_KEY_MD5_LEN, NULL);
-    assert(jsonData != NULL);
-    jsonData += CHAR_BYTES;   // jump type
+    // jsonData == NULL for ? operation
+    if(jsonData != NULL); jsonData += CHAR_BYTES;   // jump type
     *data = jsonData;
   }