diff --git a/source/dnode/vnode/src/tsdb/tsdbMergeTree.c b/source/dnode/vnode/src/tsdb/tsdbMergeTree.c
index d4af0422d781f4560abe9ef7fe28353ff99fee0c..d9d60442ffbfd36dfa9b132b4d5f9c714558de7a 100644
--- a/source/dnode/vnode/src/tsdb/tsdbMergeTree.c
+++ b/source/dnode/vnode/src/tsdb/tsdbMergeTree.c
@@ -404,7 +404,7 @@ void tLDataIterNextBlock(SLDataIter *pIter, const char *idStr) {
     tsdbDebug("try next last file block:%d from %d, trigger by uid:%" PRIu64 ", file index:%d, %s", pIter->iSttBlk,
               oldIndex, pIter->uid, pIter->iStt, idStr);
   } else {
-    tsdbDebug("no more last block qualified, uid:%" PRIu64 ", file index::%d, %s", pIter->uid, oldIndex, idStr);
+    tsdbDebug("no more last block qualified, uid:%" PRIu64 ", file index:%d, %s", pIter->uid, oldIndex, idStr);
   }
 }
 
diff --git a/source/dnode/vnode/src/tsdb/tsdbRead.c b/source/dnode/vnode/src/tsdb/tsdbRead.c
index f4929635d913231a0bef53527b6bd3bd6ffc9642..22d276b6fd226132711522a0562aae3ce967b842 100644
--- a/source/dnode/vnode/src/tsdb/tsdbRead.c
+++ b/source/dnode/vnode/src/tsdb/tsdbRead.c
@@ -44,6 +44,7 @@ typedef struct SBlockIndex {
 typedef struct STableBlockScanInfo {
   uint64_t  uid;
   TSKEY     lastKey;
+  TSKEY     lastKeyInStt;       // last accessed key in stt
   SMapData  mapData;            // block info (compressed)
   SArray*   pBlockList;         // block data index list, SArray<SBlockIndex>
   SIterInfo iter;               // mem buffer skip list iterator
@@ -192,7 +193,7 @@ static TSDBROW* getValidMemRow(SIterInfo* pIter, const SArray* pDelList, STsdbRe
 static int32_t  doMergeRowsInFileBlocks(SBlockData* pBlockData, STableBlockScanInfo* pScanInfo, STsdbReader* pReader,
                                         SRowMerger* pMerger);
 static int32_t  doMergeRowsInLastBlock(SLastBlockReader* pLastBlockReader, STableBlockScanInfo* pScanInfo, int64_t ts,
-                                       SRowMerger* pMerger, SVersionRange* pVerRange);
+                                       SRowMerger* pMerger, SVersionRange* pVerRange, const char* id);
 static int32_t  doMergeRowsInBuf(SIterInfo* pIter, uint64_t uid, int64_t ts, SArray* pDelList, SRowMerger* pMerger,
                                  STsdbReader* pReader);
 static int32_t  doAppendRowFromTSRow(SSDataBlock* pBlock, STsdbReader* pReader, SRow* pTSRow,
@@ -407,6 +408,7 @@ static SHashObj* createDataBlockScanInfo(STsdbReader* pTsdbReader, SBlockInfoBuf
       pScanInfo->lastKey = (ekey < INT64_MAX) ? (ekey + 1) : ekey;
     }
 
+    pScanInfo->lastKeyInStt = pScanInfo->lastKey;
     taosHashPut(pTableMap, &pScanInfo->uid, sizeof(uint64_t), &pScanInfo, POINTER_BYTES);
     tsdbTrace("%p check table uid:%" PRId64 " from lastKey:%" PRId64 " %s", pTsdbReader, pScanInfo->uid,
               pScanInfo->lastKey, pTsdbReader->idStr);
@@ -1795,21 +1797,21 @@ static bool nextRowFromLastBlocks(SLastBlockReader* pLastBlockReader, STableBloc
 
   while (1) {
     bool hasVal = tMergeTreeNext(&pLastBlockReader->mergeTree);
-    if (!hasVal) {
+    if (!hasVal) { // the next value will be the accessed key in stt
+      pScanInfo->lastKeyInStt += step;
       return false;
     }
 
     TSDBROW row = tMergeTreeGetRow(&pLastBlockReader->mergeTree);
     TSDBKEY k = TSDBROW_KEY(&row);
-    if (hasBeenDropped(pScanInfo->delSkyline, &pScanInfo->lastBlockDelIndex, &k, pLastBlockReader->order, pVerRange)) {
-      pScanInfo->lastKey = k.ts;
-    } else {
+    pScanInfo->lastKeyInStt = k.ts;
+
+    if (!hasBeenDropped(pScanInfo->delSkyline, &pScanInfo->lastBlockDelIndex, &k, pLastBlockReader->order, pVerRange)) {
       // the qualifed ts may equal to k.ts, only a greater version one.
       // here we need to fallback one step.
-      if (pScanInfo->lastKey == k.ts) {
-        pScanInfo->lastKey -= step;
-      }
-
+//      if (pScanInfo->lastKey == k.ts) {
+//        pScanInfo->lastKey -= step;
+//      }
       return true;
     }
   }
@@ -1949,7 +1951,7 @@ static int32_t doMergeBufAndFileRows(STsdbReader* pReader, STableBlockScanInfo*
           return code;
         }
       }
-      doMergeRowsInLastBlock(pLastBlockReader, pBlockScanInfo, tsLast, &merge, &pReader->verRange);
+      doMergeRowsInLastBlock(pLastBlockReader, pBlockScanInfo, tsLast, &merge, &pReader->verRange, pReader->idStr);
     }
 
     if (minKey == k.ts) {
@@ -1997,7 +1999,7 @@ static int32_t doMergeBufAndFileRows(STsdbReader* pReader, STableBlockScanInfo*
           return code;
         }
       }
-      doMergeRowsInLastBlock(pLastBlockReader, pBlockScanInfo, tsLast, &merge, &pReader->verRange);
+      doMergeRowsInLastBlock(pLastBlockReader, pBlockScanInfo, tsLast, &merge, &pReader->verRange, pReader->idStr);
     }
 
     if (minKey == key) {
@@ -2050,7 +2052,7 @@ static int32_t doMergeFileBlockAndLastBlock(SLastBlockReader* pLastBlockReader,
 
       TSDBROW fRow1 = tMergeTreeGetRow(&pLastBlockReader->mergeTree);
       tsdbRowMerge(&merge, &fRow1);
-      doMergeRowsInLastBlock(pLastBlockReader, pBlockScanInfo, tsLastBlock, &merge, &pReader->verRange);
+      doMergeRowsInLastBlock(pLastBlockReader, pBlockScanInfo, tsLastBlock, &merge, &pReader->verRange, pReader->idStr);
 
       code = tsdbRowMergerGetRow(&merge, &pTSRow);
       if (code != TSDB_CODE_SUCCESS) {
@@ -2068,7 +2070,7 @@ static int32_t doMergeFileBlockAndLastBlock(SLastBlockReader* pLastBlockReader,
       return code;
     }
 
-    doMergeRowsInLastBlock(pLastBlockReader, pBlockScanInfo, tsLastBlock, &merge, &pReader->verRange);
+    doMergeRowsInLastBlock(pLastBlockReader, pBlockScanInfo, tsLastBlock, &merge, &pReader->verRange, pReader->idStr);
 
     // merge with block data if ts == key
     if (tsLastBlock == pBlockData->aTSKEY[pDumpInfo->rowIndex]) {
@@ -2121,7 +2123,7 @@ static int32_t mergeFileBlockAndLastBlock(STsdbReader* pReader, SLastBlockReader
         TSDBROW fRow1 = tMergeTreeGetRow(&pLastBlockReader->mergeTree);
         tsdbRowMerge(&merge, &fRow1);
 
-        doMergeRowsInLastBlock(pLastBlockReader, pBlockScanInfo, ts, &merge, &pReader->verRange);
+        doMergeRowsInLastBlock(pLastBlockReader, pBlockScanInfo, ts, &merge, &pReader->verRange, pReader->idStr);
 
         code = tsdbRowMergerGetRow(&merge, &pTSRow);
         if (code != TSDB_CODE_SUCCESS) {
@@ -2230,7 +2232,7 @@ static int32_t doMergeMultiLevelRows(STsdbReader* pReader, STableBlockScanInfo*
         }
       }
 
-      doMergeRowsInLastBlock(pLastBlockReader, pBlockScanInfo, tsLast, &merge, &pReader->verRange);
+      doMergeRowsInLastBlock(pLastBlockReader, pBlockScanInfo, tsLast, &merge, &pReader->verRange, pReader->idStr);
     }
 
     if (minKey == ik.ts) {
@@ -2321,7 +2323,7 @@ static int32_t doMergeMultiLevelRows(STsdbReader* pReader, STableBlockScanInfo*
           return code;
         }
       }
-      doMergeRowsInLastBlock(pLastBlockReader, pBlockScanInfo, tsLast, &merge, &pReader->verRange);
+      doMergeRowsInLastBlock(pLastBlockReader, pBlockScanInfo, tsLast, &merge, &pReader->verRange, pReader->idStr);
     }
 
     if (minKey == key) {
@@ -2472,9 +2474,9 @@ static bool initLastBlockReader(SLastBlockReader* pLBlockReader, STableBlockScan
   int32_t     step = ASCENDING_TRAVERSE(pLBlockReader->order) ? 1 : -1;
   STimeWindow w = pLBlockReader->window;
   if (ASCENDING_TRAVERSE(pLBlockReader->order)) {
-    w.skey = pScanInfo->lastKey + step;
+    w.skey = pScanInfo->lastKeyInStt;
   } else {
-    w.ekey = pScanInfo->lastKey + step;
+    w.ekey = pScanInfo->lastKeyInStt;
   }
 
   tsdbDebug("init last block reader, window:%" PRId64 "-%" PRId64 ", uid:%" PRIu64 ", %s", w.skey, w.ekey,
@@ -3567,13 +3569,16 @@ int32_t doMergeRowsInFileBlocks(SBlockData* pBlockData, STableBlockScanInfo* pSc
 }
 
 int32_t doMergeRowsInLastBlock(SLastBlockReader* pLastBlockReader, STableBlockScanInfo* pScanInfo, int64_t ts,
-                               SRowMerger* pMerger, SVersionRange* pVerRange) {
+                               SRowMerger* pMerger, SVersionRange* pVerRange, const char* idStr) {
   while (nextRowFromLastBlocks(pLastBlockReader, pScanInfo, pVerRange)) {
     int64_t next1 = getCurrentKeyInLastBlock(pLastBlockReader);
     if (next1 == ts) {
       TSDBROW fRow1 = tMergeTreeGetRow(&pLastBlockReader->mergeTree);
       tsdbRowMerge(pMerger, &fRow1);
     } else {
+      tsdbTrace("uid:%" PRIu64 " last del index:%d, del range:%d, lastKeyInStt:%" PRId64 ", %s", pScanInfo->uid,
+                pScanInfo->lastBlockDelIndex, (int32_t)taosArrayGetSize(pScanInfo->delSkyline), pScanInfo->lastKeyInStt,
+                idStr);
       break;
     }
   }