diff --git a/source/dnode/mnode/impl/src/mndTopic.c b/source/dnode/mnode/impl/src/mndTopic.c
index f1ee7bca3ba5c960adc66154e4b25aca6febbfc2..4d12f2433fc0b37c3407a5f2cf08fe601b86bcab 100644
--- a/source/dnode/mnode/impl/src/mndTopic.c
+++ b/source/dnode/mnode/impl/src/mndTopic.c
@@ -912,12 +912,14 @@ static int32_t mndRetrieveTopic(SRpcMsg *pReq, SShowObj *pShow, SSDataBlock *pBl
     pColInfo = taosArrayGet(pBlock->pDataBlock, cols++);
     colDataSetVal(pColInfo, numOfRows, (const char *)&pTopic->createTime, false);
 
-    char sql[TSDB_SHOW_SQL_LEN + VARSTR_HEADER_SIZE] = {0};
+    char *sql = taosMemoryMalloc(strlen(pTopic->sql) + VARSTR_HEADER_SIZE);
     STR_TO_VARSTR(sql, pTopic->sql);
 
     pColInfo = taosArrayGet(pBlock->pDataBlock, cols++);
     colDataSetVal(pColInfo, numOfRows, (const char *)sql, false);
 
+    taosMemoryFree(sql);
+
     char *schemaJson = taosMemoryMalloc(TSDB_SHOW_SCHEMA_JSON_LEN + VARSTR_HEADER_SIZE);
     if(pTopic->subType == TOPIC_SUB_TYPE__COLUMN){
       schemaToJson(pTopic->schema.pSchema, pTopic->schema.nCols, schemaJson);