diff --git a/source/dnode/vnode/src/tsdb/tsdbRead2.c b/source/dnode/vnode/src/tsdb/tsdbRead2.c
index 52ee6d0b14..ea8801bf1f 100644
--- a/source/dnode/vnode/src/tsdb/tsdbRead2.c
+++ b/source/dnode/vnode/src/tsdb/tsdbRead2.c
@@ -76,6 +76,8 @@ static void          updateComposedBlockInfo(STsdbReader* pReader, double el, ST
 
 static bool outOfTimeWindow(int64_t ts, STimeWindow* pWindow) { return (ts > pWindow->ekey) || (ts < pWindow->skey); }
 
+static void resetProcMemTableListIndex(SReaderStatus* pStatus);
+
 static int32_t setColumnIdSlotList(SBlockLoadSuppInfo* pSupInfo, SColumnInfo* pCols, const int32_t* pSlotIdList,
                                    int32_t numOfCols) {
   pSupInfo->smaValid = true;
@@ -2565,7 +2567,9 @@ static void prepareDurationForNextFileSet(STsdbReader* pReader) {
   }
 
   if (pReader->status.bProcMemPreFileset) {
-    resetTableListIndex(&pReader->status);
+    uInfo("has mem preset");
+    pReader->status.procMemUidList.tableUidList = pReader->status.uidList.tableUidList;
+    resetProcMemTableListIndex(&pReader->status);
   }
 
   if (!pReader->status.bProcMemPreFileset) {
@@ -2573,6 +2577,7 @@ static void prepareDurationForNextFileSet(STsdbReader* pReader) {
       STsdReaderNotifyInfo info = {0};
       info.duration.filesetId = fid;
       pReader->notifyFn(TSD_READER_NOTIFY_DURATION_START, &info, pReader->notifyParam);
+      uInfo("new duration notification. %d", fid);
     }
   }
 
@@ -2643,6 +2648,14 @@ static void resetTableListIndex(SReaderStatus* pStatus) {
   pStatus->pTableIter = tSimpleHashGet(pStatus->pTableMap, &uid, sizeof(uid));
 }
 
+static void resetProcMemTableListIndex(SReaderStatus* pStatus) {
+  STableUidList* pList = &pStatus->procMemUidList;
+
+  pList->currentIndex = 0;
+  uint64_t uid = pList->tableUidList[0];
+  pStatus->pProcMemTableIter = tSimpleHashGet(pStatus->pTableMap, &uid, sizeof(uid));
+}
+
 static bool moveToNextTable(STableUidList* pOrderedCheckInfo, SReaderStatus* pStatus) {
   pOrderedCheckInfo->currentIndex += 1;
   if (pOrderedCheckInfo->currentIndex >= tSimpleHashGetSize(pStatus->pTableMap)) {
@@ -2655,6 +2668,18 @@ static bool moveToNextTable(STableUidList* pOrderedCheckInfo, SReaderStatus* pSt
   return (pStatus->pTableIter != NULL);
 }
 
+static bool moveToNextTablePreFileSet(STableUidList* pOrderedCheckInfo, SReaderStatus* pStatus) {
+  pOrderedCheckInfo->currentIndex += 1;
+  if (pOrderedCheckInfo->currentIndex >= tSimpleHashGetSize(pStatus->pTableMap)) {
+    pStatus->pProcMemTableIter = NULL;
+    return false;
+  }
+
+  uint64_t uid = pOrderedCheckInfo->tableUidList[pOrderedCheckInfo->currentIndex];
+  pStatus->pProcMemTableIter = tSimpleHashGet(pStatus->pTableMap, &uid, sizeof(uid));
+  return (pStatus->pProcMemTableIter != NULL);
+}
+
 static int32_t doLoadSttBlockSequentially(STsdbReader* pReader) {
   SReaderStatus*   pStatus = &pReader->status;
   SSttBlockReader* pSttBlockReader = pStatus->fileIter.pSttBlockReader;
@@ -2889,6 +2914,48 @@ static int32_t doBuildDataBlock(STsdbReader* pReader) {
   return (pReader->code != TSDB_CODE_SUCCESS) ? pReader->code : code;
 }
 
+static int32_t buildBlockFromBufferPreFilesetSequentially(STsdbReader* pReader, int64_t endKey) {
+  SReaderStatus* pStatus = &pReader->status;
+  STableUidList* pUidList = &pStatus->procMemUidList;
+
+  tsdbDebug("seq load data blocks from cache, %s", pReader->idStr);
+
+  while (1) {
+    if (pReader->code != TSDB_CODE_SUCCESS) {
+      tsdbWarn("tsdb reader is stopped ASAP, code:%s, %s", strerror(pReader->code), pReader->idStr);
+      return pReader->code;
+    }
+
+    STableBlockScanInfo** pBlockScanInfo = pStatus->pProcMemTableIter;
+    if (pReader->pIgnoreTables &&
+        taosHashGet(*pReader->pIgnoreTables, &(*pBlockScanInfo)->uid, sizeof((*pBlockScanInfo)->uid))) {
+      bool hasNexTable = moveToNextTablePreFileSet(pUidList, pStatus);
+      if (!hasNexTable) {
+        return TSDB_CODE_SUCCESS;
+      }
+      continue;
+    }
+
+    initMemDataIterator(*pBlockScanInfo, pReader);
+    initDelSkylineIterator(*pBlockScanInfo, pReader->info.order, &pReader->cost);
+
+    int32_t code = buildDataBlockFromBuf(pReader, *pBlockScanInfo, endKey);
+    if (code != TSDB_CODE_SUCCESS) {
+      return code;
+    }
+
+    if (pReader->resBlockInfo.pResBlock->info.rows > 0) {
+      return TSDB_CODE_SUCCESS;
+    }
+
+    // current table is exhausted, let's try next table
+    bool hasNexTable = moveToNextTablePreFileSet(pUidList, pStatus);
+    if (!hasNexTable) {
+      return TSDB_CODE_SUCCESS;
+    }
+  }
+}
+
 static int32_t buildBlockFromBufferSequentially(STsdbReader* pReader, int64_t endKey) {
   SReaderStatus* pStatus = &pReader->status;
   STableUidList* pUidList = &pStatus->uidList;
@@ -4244,6 +4311,37 @@ _err:
   return code;
 }
 
+static int32_t buildMemoryBlockPreFileset(STsdbReader* pReader) {
+  int32_t code = TSDB_CODE_SUCCESS;
+  SReaderStatus* pStatus = &pReader->status;
+
+  SSDataBlock* pBlock = pReader->resBlockInfo.pResBlock;
+
+  int32_t        fid = pReader->status.pCurrentFileset->fid;
+  STimeWindow    win = {0};
+  tsdbFidKeyRange(fid, pReader->pTsdb->keepCfg.days, pReader->pTsdb->keepCfg.precision, &win.skey, &win.ekey);
+
+  int64_t endKey = (ASCENDING_TRAVERSE(pReader->info.order)) ? win.skey : win.ekey;
+  code = buildBlockFromBufferPreFilesetSequentially(pReader, endKey);
+  uInfo("zsl mem block rows: %ld", pBlock->info.rows);
+  if (code != TSDB_CODE_SUCCESS || pBlock->info.rows > 0) {
+    return code;
+  } else {
+    pStatus->bProcMemPreFileset = false;
+    if (pReader->notifyFn) {
+      STsdReaderNotifyInfo info = {0};
+      info.duration.filesetId = fid;
+      pReader->notifyFn(TSD_READER_NOTIFY_DURATION_START, &info, pReader->notifyParam);
+      uInfo("new duration notification. mem pre fileset : %d", fid);
+    }
+    if (pStatus->pNextFileBlock && pStatus->pNextFileBlock->info.rows > 0) {
+      copyDataBlock(pBlock, pStatus->pNextFileBlock);
+      blockDataDestroy(pStatus->pNextFileBlock);
+    }
+  }
+  return code;
+}
+
 static int32_t doTsdbNextDataBlockFilesetDelimited(STsdbReader* pReader) {
   SReaderStatus* pStatus = &pReader->status;
   int32_t code = TSDB_CODE_SUCCESS;
@@ -4251,22 +4349,9 @@ static int32_t doTsdbNextDataBlockFilesetDelimited(STsdbReader* pReader) {
 
   if (pStatus->loadFromFile) {
     if (pStatus->bProcMemPreFileset) {
-      int32_t fid = pReader->status.pCurrentFileset->fid;
-      STimeWindow win = {0};
-      tsdbFidKeyRange(fid, pReader->pTsdb->keepCfg.days, pReader->pTsdb->keepCfg.precision, &win.skey, &win.ekey);
-
-      int64_t endKey = (ASCENDING_TRAVERSE(pReader->info.order)) ? win.skey : win.ekey;
-      code = buildBlockFromBufferSequentially(pReader, endKey);
+      code = buildMemoryBlockPreFileset(pReader);
       if (code != TSDB_CODE_SUCCESS || pBlock->info.rows > 0) {
         return code;
-      } else {
-        pStatus->bProcMemPreFileset = false;
-        if (pReader->notifyFn) {
-          STsdReaderNotifyInfo info = {0};
-          info.duration.filesetId = fid;
-          pReader->notifyFn(TSD_READER_NOTIFY_DURATION_START, &info, pReader->notifyParam);
-        }
-        resetTableListIndex(pStatus);
       }
     }
 
@@ -4274,6 +4359,17 @@ static int32_t doTsdbNextDataBlockFilesetDelimited(STsdbReader* pReader) {
     if (code != TSDB_CODE_SUCCESS) {
       return code;
     }
+    if (pStatus->bProcMemPreFileset && pBlock->info.rows > 0) {
+      pStatus->pNextFileBlock = createOneDataBlock(pBlock, true);
+      blockDataCleanup(pBlock);
+      code = buildMemoryBlockPreFileset(pReader);
+      if (code != TSDB_CODE_SUCCESS || pBlock->info.rows > 0) {
+        return code;
+      }
+    }
+    
+
+    uInfo("zsl file block rows %ld", pBlock->info.rows);
 
     if (pBlock->info.rows <= 0) {
       resetTableListIndex(&pReader->status);
diff --git a/source/dnode/vnode/src/tsdb/tsdbReadUtil.h b/source/dnode/vnode/src/tsdb/tsdbReadUtil.h
index 43cd499aca..09ab064806 100644
--- a/source/dnode/vnode/src/tsdb/tsdbReadUtil.h
+++ b/source/dnode/vnode/src/tsdb/tsdbReadUtil.h
@@ -216,6 +216,9 @@ typedef struct SReaderStatus {
   int64_t               prevFilesetStartKey;
   int64_t               prevFilesetEndKey;
   bool                  bProcMemFirstFileset;
+  STableUidList         procMemUidList;
+  STableBlockScanInfo** pProcMemTableIter;
+  SSDataBlock*           pNextFileBlock;
 } SReaderStatus;
 
 struct STsdbReader {