fix(query): step forward index

source/dnode/vnode/src/tsdb/tsdbRead.c

@@ -1446,9 +1446,9 @@ static int32_t buildComposedDataBlockImpl(STsdbReader* pReader, STableBlockScanI
         (pDumpInfo->rowIndex > 0 && pReader->order == TSDB_ORDER_DESC)) {
       int32_t step = pReader->order == TSDB_ORDER_ASC? 1:-1;
       int64_t nextKey = pBlockData->aTSKEY[pDumpInfo->rowIndex + step];
-      if (nextKey != key) {
-        // merge is not needed
+      if (nextKey != key) { // merge is not needed
         doAppendRowFromBlock(pReader->pResBlock, pReader, pBlockData, pDumpInfo->rowIndex);
+        pDumpInfo->rowIndex += step;
         return TSDB_CODE_SUCCESS;
       }
     }