diff --git a/src/client/src/tscUtil.c b/src/client/src/tscUtil.c
index 259bcd4cbd2e63f52c33f072908ef647731d750e..26a81c597f077e5101b3920e792c650d00ca50f3 100644
--- a/src/client/src/tscUtil.c
+++ b/src/client/src/tscUtil.c
@@ -625,18 +625,31 @@ static int trimDataBlock(void* pDataBlock, STableDataBlocks* pTableDataBlock, bo
   return len;
 }
 
+static int32_t getRowExpandSize(STableMeta* pTableMeta) {
+  int32_t result = TD_DATA_ROW_HEAD_SIZE;
+  int32_t columns = tscGetNumOfColumns(pTableMeta);
+  SSchema* pSchema = tscGetTableSchema(pTableMeta);
+  for(int32_t i = 0; i < columns; i++) {
+    if (IS_VAR_DATA_TYPE((pSchema + i)->type)) {
+      result += TYPE_BYTES[TSDB_DATA_TYPE_BINARY];
+    }
+  }
+  return result;
+}
+
 int32_t tscMergeTableDataBlocks(SSqlObj* pSql, SArray* pTableDataBlockList) {
   SSqlCmd* pCmd = &pSql->cmd;
 
   // the maximum expanded size in byte when a row-wise data is converted to SDataRow format
-  const int32_t MAX_EXPAND_SIZE = TD_DATA_ROW_HEAD_SIZE + TYPE_BYTES[TSDB_DATA_TYPE_BINARY];
+  STableDataBlocks* pOneTableBlock = taosArrayGetP(pTableDataBlockList, 0);
+  int32_t expandSize = getRowExpandSize(pOneTableBlock->pTableMeta);
 
   void* pVnodeDataBlockHashList = taosHashInit(128, taosGetDefaultHashFunction(TSDB_DATA_TYPE_BIGINT), false);
   SArray* pVnodeDataBlockList = taosArrayInit(8, POINTER_BYTES);
 
   size_t total = taosArrayGetSize(pTableDataBlockList);
   for (int32_t i = 0; i < total; ++i) {
-    STableDataBlocks* pOneTableBlock = taosArrayGetP(pTableDataBlockList, i);
+    pOneTableBlock = taosArrayGetP(pTableDataBlockList, i);
     STableDataBlocks* dataBuf = NULL;
     
     int32_t ret =
@@ -650,7 +663,7 @@ int32_t tscMergeTableDataBlocks(SSqlObj* pSql, SArray* pTableDataBlockList) {
     }
 
     SSubmitBlk* pBlocks = (SSubmitBlk*) pOneTableBlock->pData;
-    int64_t destSize = dataBuf->size + pOneTableBlock->size + pBlocks->numOfRows * MAX_EXPAND_SIZE;
+    int64_t destSize = dataBuf->size + pOneTableBlock->size + pBlocks->numOfRows * expandSize;
 
     if (dataBuf->nAllocSize < destSize) {
       while (dataBuf->nAllocSize < destSize) {
@@ -678,8 +691,7 @@ int32_t tscMergeTableDataBlocks(SSqlObj* pSql, SArray* pTableDataBlockList) {
     tscDebug("%p tableId:%s, sid:%d rows:%d sversion:%d skey:%" PRId64 ", ekey:%" PRId64, pSql, pOneTableBlock->tableId,
         pBlocks->tid, pBlocks->numOfRows, pBlocks->sversion, GET_INT64_VAL(pBlocks->data), GET_INT64_VAL(ekey));
 
-
-    int32_t len = pBlocks->numOfRows * (pOneTableBlock->rowSize + MAX_EXPAND_SIZE);
+    int32_t len = pBlocks->numOfRows * (pOneTableBlock->rowSize + expandSize);
 
     pBlocks->tid = htonl(pBlocks->tid);
     pBlocks->uid = htobe64(pBlocks->uid);