diff --git a/source/dnode/vnode/src/tsdb/tsdbRead.c b/source/dnode/vnode/src/tsdb/tsdbRead.c
index 6400e7534bb7ffd20f961c16a85e96c85c36c3d8..e9bb7e3d09bc669d531d7df83fcb6902f2805bbd 100644
--- a/source/dnode/vnode/src/tsdb/tsdbRead.c
+++ b/source/dnode/vnode/src/tsdb/tsdbRead.c
@@ -423,19 +423,6 @@ static STimeWindow updateQueryTimeWindow(STsdb* pTsdb, STimeWindow* pWindow) {
   return win;
 }
 
-static void limitOutputBufferSize(const SQueryTableDataCond* pCond, int32_t* capacity) {
-  int32_t rowLen = 0;
-  for (int32_t i = 0; i < pCond->numOfCols; ++i) {
-    rowLen += pCond->colList[i].bytes;
-  }
-
-  // make sure the output SSDataBlock size be less than 2MB.
-  const int32_t TWOMB = 2 * 1024 * 1024;
-  if ((*capacity) * rowLen > TWOMB) {
-    (*capacity) = TWOMB / rowLen;
-  }
-}
-
 // init file iterator
 static int32_t initFilesetIterator(SFilesetIter* pIter, SArray* aDFileSet, STsdbReader* pReader) {
   size_t numOfFileset = taosArrayGetSize(aDFileSet);
@@ -618,9 +605,6 @@ static int32_t tsdbReaderCreate(SVnode* pVnode, SQueryTableDataCond* pCond, STsd
     goto _end;
   }
 
-  // todo refactor.
-  limitOutputBufferSize(pCond, &pReader->capacity);
-
   // allocate buffer in order to load data blocks from file
   SBlockLoadSuppInfo* pSup = &pReader->suppInfo;
   pSup->pColAgg = taosArrayInit(pCond->numOfCols, sizeof(SColumnDataAgg));
@@ -3835,11 +3819,9 @@ int32_t tsdbReaderOpen(SVnode* pVnode, SQueryTableDataCond* pCond, void* pTableL
     pCond->twindows.ekey -= 1;
   }
 
-  int32_t capacity = 0;
-  if (pResBlock == NULL) {
-    capacity = 4096;
-  } else {
-    capacity = pResBlock->info.capacity;
+  int32_t capacity = pVnode->config.tsdbCfg.maxRows;
+  if (pResBlock != NULL) {
+    blockDataEnsureCapacity(pResBlock, capacity);
   }
 
   int32_t code = tsdbReaderCreate(pVnode, pCond, ppReader, capacity, pResBlock, idstr);
diff --git a/source/libs/executor/src/scanoperator.c b/source/libs/executor/src/scanoperator.c
index f90cc6699b61f0edaf459169421fa902f589ada5..29fe9817c915371367d45dc7ef561386aab52d6a 100644
--- a/source/libs/executor/src/scanoperator.c
+++ b/source/libs/executor/src/scanoperator.c
@@ -781,6 +781,10 @@ static SSDataBlock* doTableScan(SOperatorInfo* pOperator) {
       if (code != TSDB_CODE_SUCCESS) {
         T_LONG_JMP(pTaskInfo->env, code);
       }
+
+      if (pInfo->pResBlock->info.capacity > pOperator->resultInfo.capacity) {
+        pOperator->resultInfo.capacity = pInfo->pResBlock->info.capacity;
+      }
     }
 
     SSDataBlock* result = doGroupedTableScan(pOperator);
@@ -884,7 +888,7 @@ SOperatorInfo* createTableScanOperatorInfo(STableScanPhysiNode* pTableScanNode,
 
   initResultSizeInfo(&pOperator->resultInfo, 4096);
   pInfo->pResBlock = createDataBlockFromDescNode(pDescNode);
-  blockDataEnsureCapacity(pInfo->pResBlock, pOperator->resultInfo.capacity);
+//  blockDataEnsureCapacity(pInfo->pResBlock, pOperator->resultInfo.capacity);
 
   code = filterInitFromNode((SNode*)pTableScanNode->scan.node.pConditions, &pOperator->exprSupp.pFilterInfo, 0);
   if (code != TSDB_CODE_SUCCESS) {