diff --git a/source/common/src/tdatablock.c b/source/common/src/tdatablock.c
index 565f8da0a0635d331da3f3f432c60adab8d2f254..40e21fc6ac2d73aacdbb93d35bbaa4fdfd312a34 100644
--- a/source/common/src/tdatablock.c
+++ b/source/common/src/tdatablock.c
@@ -463,7 +463,7 @@ SSDataBlock* blockDataExtractBlock(SSDataBlock* pBlock, int32_t startIndex, int3
   }
 
   pDst->info = pBlock->info;
-
+  pDst->info.rows = 0;
   size_t numOfCols = taosArrayGetSize(pBlock->pDataBlock);
   for (int32_t i = 0; i < numOfCols; ++i) {
     SColumnInfoData  colInfo = {0};
diff --git a/source/libs/function/src/tudf.c b/source/libs/function/src/tudf.c
index aead5f2867417265acbf061dcf21c1c7fc86a1ad..da9474ede0ff75010f7d23dbac0d18f6d29144e4 100644
--- a/source/libs/function/src/tudf.c
+++ b/source/libs/function/src/tudf.c
@@ -763,6 +763,7 @@ void freeUdfInterBuf(SUdfInterBuf *buf) {
 
 int32_t convertDataBlockToUdfDataBlock(SSDataBlock *block, SUdfDataBlock *udfBlock) {
   udfBlock->numOfRows = block->info.rows;
+  udfBlock->numOfCols = taosArrayGetSize(block->pDataBlock);
   udfBlock->udfCols = taosMemoryCalloc(taosArrayGetSize(block->pDataBlock), sizeof(SUdfColumn*));
   for (int32_t i = 0; i < udfBlock->numOfCols; ++i) {
     udfBlock->udfCols[i] = taosMemoryCalloc(1, sizeof(SUdfColumn));