diff --git a/source/common/src/tdatablock.c b/source/common/src/tdatablock.c
index 3c8d394b4396776b03d3557e49aa7d87c29ffccc..a75046d06d04fc229244031e80c0e28bd72e7dd2 100644
--- a/source/common/src/tdatablock.c
+++ b/source/common/src/tdatablock.c
@@ -1180,7 +1180,7 @@ void blockDataCleanup(SSDataBlock* pDataBlock) {
 
 void blockDataEmpty(SSDataBlock* pDataBlock) {
   SDataBlockInfo* pInfo = &pDataBlock->info;
-  if (pInfo->capacity == 0 || pInfo->rows > pDataBlock->info.capacity) {
+  if (pInfo->capacity == 0) {
     return;
   }
 
diff --git a/source/dnode/vnode/src/tsdb/tsdbRead.c b/source/dnode/vnode/src/tsdb/tsdbRead.c
index 96bce02b674476b760114099de9d93eb0a735d72..c6444b5ded690619919261cc228cc9bb4850d787 100644
--- a/source/dnode/vnode/src/tsdb/tsdbRead.c
+++ b/source/dnode/vnode/src/tsdb/tsdbRead.c
@@ -24,6 +24,11 @@ typedef enum {
   EXTERNAL_ROWS_NEXT = 0x3,
 } EContentData;
 
+typedef enum {
+  READ_MODE_COUNT_ONLY = 0x1,
+  READ_MODE_ALL,
+} EReadMode;
+
 typedef struct {
   STbDataIter* iter;
   int32_t      index;
@@ -167,6 +172,8 @@ struct STsdbReader {
   uint64_t           suid;
   int16_t            order;
   bool               freeBlock;
+  EReadMode          readMode;
+  uint64_t           rowsNum;
   STimeWindow        window;  // the primary query time window that applies to all queries
   SSDataBlock*       pResBlock;
   int32_t            capacity;
@@ -2998,6 +3005,9 @@ static int32_t doBuildDataBlock(STsdbReader* pReader) {
   TSDBKEY keyInBuf = getCurrentKeyInBuf(pScanInfo, pReader);
 
   if (fileBlockShouldLoad(pReader, pBlockInfo, pBlock, pScanInfo, keyInBuf, pLastBlockReader)) {
+    if (READ_MODE_COUNT_ONLY == pReader->readMode && pReader->rowsNum > 0) {
+      return code;
+    }
     code = doLoadFileBlockData(pReader, pBlockIter, &pStatus->fileBlockData, pScanInfo->uid);
     if (code != TSDB_CODE_SUCCESS) {
       return code;
@@ -3006,12 +3016,19 @@ static int32_t doBuildDataBlock(STsdbReader* pReader) {
     // build composed data block
     code = buildComposedDataBlock(pReader);
   } else if (bufferDataInFileBlockGap(pReader->order, keyInBuf, pBlock)) {
+    if (READ_MODE_COUNT_ONLY == pReader->readMode && pReader->rowsNum > 0) {
+      return code;
+    }
     // data in memory that are earlier than current file block
     // rows in buffer should be less than the file block in asc, greater than file block in desc
     int64_t endKey = (ASCENDING_TRAVERSE(pReader->order)) ? pBlock->minKey.ts : pBlock->maxKey.ts;
     code = buildDataBlockFromBuf(pReader, pScanInfo, endKey);
   } else {
     if (hasDataInLastBlock(pLastBlockReader) && !ASCENDING_TRAVERSE(pReader->order)) {
+      if (READ_MODE_COUNT_ONLY == pReader->readMode && pReader->rowsNum > 0) {
+        return code;
+      }
+
       // only return the rows in last block
       int64_t tsLast = getCurrentKeyInLastBlock(pLastBlockReader);
       ASSERT(tsLast >= pBlock->maxKey.ts);
@@ -3069,6 +3086,131 @@ static int32_t doBuildDataBlock(STsdbReader* pReader) {
   return code;
 }
 
+
+static int32_t doSumBlockRows(STsdbReader* pReader, SDataFReader* pFileReader) {
+  int64_t    st = taosGetTimestampUs();
+  LRUHandle* handle = NULL;
+  int32_t    code = tsdbCacheGetBlockIdx(pFileReader->pTsdb->biCache, pFileReader, &handle);
+  if (code != TSDB_CODE_SUCCESS || handle == NULL) {
+    goto _end;
+  }
+
+  int32_t numOfTables = taosHashGetSize(pReader->status.pTableMap);
+
+  SArray* aBlockIdx = (SArray*)taosLRUCacheValue(pFileReader->pTsdb->biCache, handle);
+  size_t  num = taosArrayGetSize(aBlockIdx);
+  if (num == 0) {
+    tsdbBICacheRelease(pFileReader->pTsdb->biCache, handle);
+    return TSDB_CODE_SUCCESS;
+  }
+
+  SBlockIdx*     pBlockIdx = NULL;
+  int32_t i = 0;
+  for (int32_t i = 0; i < num; ++i) {
+    pBlockIdx = (SBlockIdx*)taosArrayGet(aBlockIdx, i);
+    if (pBlockIdx->suid != pReader->suid) {
+      continue;
+    }
+
+    STableBlockScanInfo** p = taosHashGet(pReader->status.pTableMap, &pBlockIdx->uid, sizeof(pBlockIdx->uid));
+    if (p == NULL || *p == NULL) {
+      continue;
+    }
+
+    STableBlockScanInfo *pScanInfo = *p;
+    tMapDataReset(&pScanInfo->mapData);
+    tsdbReadDataBlk(pReader->pFileReader, pBlockIdx, &pScanInfo->mapData);
+
+    SDataBlk block = {0};
+    for (int32_t j = 0; j < pScanInfo->mapData.nItem; ++j) {
+      tGetDataBlk(pScanInfo->mapData.pData + pScanInfo->mapData.aOffset[j], &block);
+      pReader->rowsNum += block.nRow;
+    }
+  }
+
+_end:
+  tsdbBICacheRelease(pFileReader->pTsdb->biCache, handle);
+  return code;
+}
+
+
+static int32_t readRowsCountFromFile(STsdbReader* pReader) {
+  int32_t   code = TSDB_CODE_SUCCESS;
+
+  while (1) {
+    bool    hasNext = false;
+    int32_t code = filesetIteratorNext(&pReader->status.fileIter, pReader, &hasNext);
+    if (code) {
+      return code;
+    }
+
+    if (!hasNext) {  // no data files on disk
+      break;
+    }
+
+    code = doSumBlockRows(pReader, pReader->pFileReader);
+    if (code != TSDB_CODE_SUCCESS) {
+      return code;
+    }
+  }
+
+  pReader->status.loadFromFile = false;
+
+  return code;
+}
+
+static int32_t readRowsCountFromStt(STsdbReader* pReader) {
+  int32_t   code = TSDB_CODE_SUCCESS;
+  SLastBlockReader*    pLastBlockReader = pReader->status.fileIter.pLastBlockReader;
+  SSttBlockLoadInfo*   pBlockLoadInfo = NULL;
+
+  for (int32_t i = 0; i < pReader->pFileReader->pSet->nSttF; ++i) {  // open all last file
+    pBlockLoadInfo = &pLastBlockReader->pInfo[i];
+    
+    if (!pLastBlockReader->pInfo[i].sttBlockLoaded) {
+      pLastBlockReader->pInfo[i].sttBlockLoaded = true;
+    
+      code = tsdbReadSttBlk(pReader->pFileReader, i, pBlockLoadInfo->aSttBlk);
+      if (code) {
+        return code;
+      }
+    }
+
+    size_t size = taosArrayGetSize(pBlockLoadInfo->aSttBlk);
+  
+    if (size >= 1) {
+      SSttBlk *pStart = taosArrayGet(pBlockLoadInfo->aSttBlk, 0);
+      SSttBlk *pEnd = taosArrayGet(pBlockLoadInfo->aSttBlk, size - 1);
+  
+      // all identical
+      if (pStart->suid == pEnd->suid) {
+        if (pStart->suid != pReader->suid) {
+          // no qualified stt block existed
+          taosArrayClear(pBlockLoadInfo->aSttBlk);
+          continue;
+        }
+      } else {
+        for (int32_t i = 0; i < size; ++i) {
+          SSttBlk *p = taosArrayGet(pBlockLoadInfo->aSttBlk, i);
+          uint64_t s = p->suid;
+          if (s < pReader->suid) {
+            continue;
+          }
+  
+          if (s == pReader->suid) {
+            pReader->rowsNum += p->nRow;
+          } else if (s > pReader->suid) {
+            break;
+          }
+        }
+      }
+    }
+  }
+
+  return code;
+}
+
+
 static int32_t buildBlockFromBufferSequentially(STsdbReader* pReader) {
   SReaderStatus* pStatus = &pReader->status;
   STableUidList* pUidList = &pStatus->uidList;
@@ -3212,6 +3354,12 @@ static int32_t buildBlockFromFiles(STsdbReader* pReader) {
           initBlockDumpInfo(pReader, pBlockIter);
         } else {
           if (pReader->status.pCurrentFileset->nSttF > 0) {
+            if (READ_MODE_COUNT_ONLY == pReader->readMode && pReader->rowsNum > 0) {
+              pReader->pResBlock->info.rows = pReader->rowsNum;
+              pReader->rowsNum = 0;
+              return TSDB_CODE_SUCCESS;
+            }
+
             // data blocks in current file are exhausted, let's try the next file now
             SBlockData* pBlockData = &pReader->status.fileBlockData;
             if (pBlockData->uid != 0) {
@@ -3226,7 +3374,17 @@ static int32_t buildBlockFromFiles(STsdbReader* pReader) {
             code = initForFirstBlockInFile(pReader, pBlockIter);
 
             // error happens or all the data files are completely checked
-            if ((code != TSDB_CODE_SUCCESS) || (pReader->status.loadFromFile == false)) {
+            if (code != TSDB_CODE_SUCCESS) {
+              return code;
+            }
+
+            if (READ_MODE_COUNT_ONLY == pReader->readMode && pReader->rowsNum > 0) {
+              pReader->pResBlock->info.rows = pReader->rowsNum;
+              pReader->rowsNum = 0;
+              return TSDB_CODE_SUCCESS;
+            }
+
+            if (pReader->status.loadFromFile == false) {
               return code;
             }
 
@@ -3240,6 +3398,17 @@ static int32_t buildBlockFromFiles(STsdbReader* pReader) {
       }
 
       code = doBuildDataBlock(pReader);
+      if (READ_MODE_COUNT_ONLY == pReader->readMode) {
+        if (false == pReader->status.composedDataBlock && pDumpInfo->allDumped) {
+          pReader->rowsNum += pReader->pResBlock->info.rows;
+          pReader->pResBlock->info.rows = 0;
+          continue;
+        } else if (pReader->pResBlock->info.rows == 0 && pReader->rowsNum > 0) {
+          pReader->pResBlock->info.rows = pReader->rowsNum;
+          pReader->rowsNum = 0;
+          return TSDB_CODE_SUCCESS;
+        }
+      }
     }
 
     if (code != TSDB_CODE_SUCCESS) {
@@ -3986,6 +4155,8 @@ static int32_t doOpenReaderImpl(STsdbReader* pReader) {
   int32_t code = TSDB_CODE_SUCCESS;
   if (pStatus->fileIter.numOfFiles == 0) {
     pStatus->loadFromFile = false;
+  } else if (READ_MODE_COUNT_ONLY == pReader->readMode) {
+    // DO NOTHING
   } else {
     code = initForFirstBlockInFile(pReader, pBlockIter);
   }
@@ -4091,6 +4262,9 @@ int32_t tsdbReaderOpen(SVnode* pVnode, SQueryTableDataCond* pCond, void* pTableL
 
   pReader->suspended = true;
 
+  
+  pReader->readMode = READ_MODE_COUNT_ONLY;
+
   tsdbDebug("%p total numOfTable:%d in this query %s", pReader, numOfTables, pReader->idStr);
   return code;
 
@@ -4394,6 +4568,35 @@ _err:
   return code;
 }
 
+static bool tsdbReadRowsCountOnly(STsdbReader* pReader) {
+  int32_t code =  TSDB_CODE_SUCCESS;
+  SSDataBlock* pBlock = pReader->pResBlock;
+
+  while (1) {
+    if (pReader->status.loadFromFile == false) {
+      break;
+    }
+  
+    code = readRowsCountFromFile(pReader);
+    if (code != TSDB_CODE_SUCCESS) {
+      return false;
+    }
+
+    code = readRowsCountFromStt(pReader);
+    if (code != TSDB_CODE_SUCCESS) {
+      return false;
+    }
+  }
+
+  pBlock->info.rows = pReader->rowsNum;
+  pBlock->info.id.uid = 0;
+  pBlock->info.dataLoad = 0;
+  
+  pReader->rowsNum = 0;
+  
+  return pBlock->info.rows > 0;
+}
+
 static bool doTsdbNextDataBlock(STsdbReader* pReader) {
   // cleanup the data that belongs to the previous data block
   SSDataBlock* pBlock = pReader->pResBlock;
@@ -4404,6 +4607,10 @@ static bool doTsdbNextDataBlock(STsdbReader* pReader) {
     return false;
   }
 
+  if (READ_MODE_COUNT_ONLY == pReader->readMode) {
+    return tsdbReadRowsCountOnly(pReader);
+  }
+
   if (pStatus->loadFromFile) {
     int32_t code = buildBlockFromFiles(pReader);
     if (code != TSDB_CODE_SUCCESS) {
diff --git a/source/libs/executor/src/scanoperator.c b/source/libs/executor/src/scanoperator.c
index 5dff1abb9799f43eddd14847cbca26bc1936cc78..2af13f083d0b5e297b44d3bef9de7a43027281b7 100644
--- a/source/libs/executor/src/scanoperator.c
+++ b/source/libs/executor/src/scanoperator.c
@@ -654,9 +654,10 @@ static SSDataBlock* doTableScanImpl(SOperatorInfo* pOperator) {
       continue;
     }
 
-    ASSERT(pBlock->info.id.uid != 0);
-    pBlock->info.id.groupId = getTableGroupId(pTaskInfo->pTableInfoList, pBlock->info.id.uid);
-
+    if (pBlock->info.id.uid) {
+      pBlock->info.id.groupId = getTableGroupId(pTaskInfo->pTableInfoList, pBlock->info.id.uid);
+    }
+    
     uint32_t status = 0;
     int32_t  code = loadDataBlock(pOperator, &pTableScanInfo->base, pBlock, &status);
     if (code != TSDB_CODE_SUCCESS) {
@@ -680,7 +681,6 @@ static SSDataBlock* doTableScanImpl(SOperatorInfo* pOperator) {
     pTaskInfo->streamInfo.lastStatus.uid = pBlock->info.id.uid;
     pTaskInfo->streamInfo.lastStatus.ts = pBlock->info.window.ekey;
 
-    ASSERT(pBlock->info.id.uid != 0);
     return pBlock;
   }
   return NULL;
@@ -797,7 +797,6 @@ static SSDataBlock* doTableScan(SOperatorInfo* pOperator) {
 
     SSDataBlock* result = doGroupedTableScan(pOperator);
     if (result != NULL) {
-      ASSERT(result->info.id.uid != 0);
       return result;
     }