diff --git a/source/libs/function/src/builtins.c b/source/libs/function/src/builtins.c
index 45cfbae1ad13d348b92d8225af797f9db400fe78..1095350f9745f40fb8dfd13072095fede1f8d757 100644
--- a/source/libs/function/src/builtins.c
+++ b/source/libs/function/src/builtins.c
@@ -248,7 +248,7 @@ static int32_t translateLength(SFunctionNode* pFunc, char* pErrBuf, int32_t len)
   }
 
   pFunc->node.resType =
-      (SDataType){.bytes = tDataTypes[TSDB_DATA_TYPE_SMALLINT].bytes, .type = TSDB_DATA_TYPE_SMALLINT};
+      (SDataType){.bytes = tDataTypes[TSDB_DATA_TYPE_BIGINT].bytes, .type = TSDB_DATA_TYPE_BIGINT};
   return TSDB_CODE_SUCCESS;
 }
 
diff --git a/source/libs/scalar/src/sclfunc.c b/source/libs/scalar/src/sclfunc.c
index cf7de025cb58dc76bf1cd1d4219ea0328d71a79f..12c654740236236f414b477f83c299da23413759 100644
--- a/source/libs/scalar/src/sclfunc.c
+++ b/source/libs/scalar/src/sclfunc.c
@@ -357,7 +357,8 @@ static int32_t doLengthFunction(SScalarParam *pInput, int32_t inputNum, SScalarP
   SColumnInfoData *pInputData  = pInput->columnData;
   SColumnInfoData *pOutputData = pOutput->columnData;
 
-  int16_t *out = (int16_t *)pOutputData->pData;
+  ASSERT(pOutputData->info.type == TSDB_DATA_TYPE_BIGINT);
+  int64_t *out = (int64_t *)pOutputData->pData;
 
   for (int32_t i = 0; i < pInput->numOfRows; ++i) {
     if (colDataIsNull_s(pInputData, i)) {