diff --git a/src/client/src/tscGlobalmerge.c b/src/client/src/tscGlobalmerge.c
index d192f743e1b1acb496aae5e13d4bc544f75eb09c..cfcc5d8b0aad67c971ff66fa7ea42994ff4d3391 100644
--- a/src/client/src/tscGlobalmerge.c
+++ b/src/client/src/tscGlobalmerge.c
@@ -1004,7 +1004,7 @@ static void ensureOutputBuf(SSLimitOperatorInfo * pInfo, SSDataBlock *pResultBlo
   if (pInfo->capacity < pResultBlock->info.rows + numOfRows) {
     int32_t total = pResultBlock->info.rows + numOfRows;
 
-    int32_t num = taosArrayGetSize(pResultBlock->pDataBlock);
+    size_t num = taosArrayGetSize(pResultBlock->pDataBlock);
     for (int32_t i = 0; i < num; ++i) {
       SColumnInfoData *pInfoData = taosArrayGet(pResultBlock->pDataBlock, i);