diff --git a/source/dnode/vnode/src/inc/tsdb.h b/source/dnode/vnode/src/inc/tsdb.h
index c4e7ff92b7d11380718932d4cc79eb458019aeae..afd53b8dda18359bd5a35701c910494ea5768a63 100644
--- a/source/dnode/vnode/src/inc/tsdb.h
+++ b/source/dnode/vnode/src/inc/tsdb.h
@@ -643,6 +643,7 @@ typedef struct SSttBlockLoadInfo {
   STSchema  *pSchema;
   int16_t   *colIds;
   int32_t    numOfCols;
+  bool       sttBlockLoaded;
 } SSttBlockLoadInfo;
 
 typedef struct SMergeTree {
diff --git a/source/dnode/vnode/src/tsdb/tsdbMergeTree.c b/source/dnode/vnode/src/tsdb/tsdbMergeTree.c
index 745b877f09aa3103157cbd329af296e65e79e2d5..0b614fd2db272b3a67099fce80cdbef698b03c1b 100644
--- a/source/dnode/vnode/src/tsdb/tsdbMergeTree.c
+++ b/source/dnode/vnode/src/tsdb/tsdbMergeTree.c
@@ -72,6 +72,7 @@ void resetLastBlockLoadInfo(SSttBlockLoadInfo *pLoadInfo) {
 
     pLoadInfo[i].elapsedTime = 0;
     pLoadInfo[i].loadBlocks = 0;
+    pLoadInfo[i].sttBlockLoaded = false;
   }
 }
 
@@ -278,9 +279,10 @@ int32_t tLDataIterOpen(struct SLDataIter **pIter, SDataFReader *pReader, int32_t
 
   (*pIter)->pBlockLoadInfo = pBlockLoadInfo;
 
-  size_t size = taosArrayGetSize(pBlockLoadInfo->aSttBlk);
-  if (size == 0) {
+//  size_t size = taosArrayGetSize(pBlockLoadInfo->aSttBlk);
+  if (!pBlockLoadInfo->sttBlockLoaded) {
     int64_t st = taosGetTimestampUs();
+    pBlockLoadInfo->sttBlockLoaded = true;
 
     code = tsdbReadSttBlk(pReader, iStt, pBlockLoadInfo->aSttBlk);
     if (code) {
@@ -288,7 +290,7 @@ int32_t tLDataIterOpen(struct SLDataIter **pIter, SDataFReader *pReader, int32_t
     }
 
     // only apply to the child tables, ordinary tables will not incur this filter procedure.
-    size = taosArrayGetSize(pBlockLoadInfo->aSttBlk);
+    size_t size = taosArrayGetSize(pBlockLoadInfo->aSttBlk);
 
     if (size >= 1) {
       SSttBlk *pStart = taosArrayGet(pBlockLoadInfo->aSttBlk, 0);
@@ -296,10 +298,10 @@ int32_t tLDataIterOpen(struct SLDataIter **pIter, SDataFReader *pReader, int32_t
 
       // all identical
       if (pStart->suid == pEnd->suid) {
-        if (pStart->suid == suid) {
-          // do nothing
-        } else if (pStart->suid != suid) {
+        if (pStart->suid != suid) {
           // no qualified stt block existed
+          taosArrayClear(pBlockLoadInfo->aSttBlk);
+
           (*pIter)->iSttBlk = -1;
           double el = (taosGetTimestampUs() - st) / 1000.0;
           tsdbDebug("load the last file info completed, elapsed time:%.2fms, %s", el, idStr);
@@ -330,7 +332,7 @@ int32_t tLDataIterOpen(struct SLDataIter **pIter, SDataFReader *pReader, int32_t
     tsdbDebug("load the last file info completed, elapsed time:%.2fms, %s", el, idStr);
   }
 
-  size = taosArrayGetSize(pBlockLoadInfo->aSttBlk);
+  size_t size = taosArrayGetSize(pBlockLoadInfo->aSttBlk);
 
   // find the start block
   (*pIter)->iSttBlk = binarySearchForStartBlock(pBlockLoadInfo->aSttBlk->pData, size, uid, backward);
diff --git a/source/dnode/vnode/src/tsdb/tsdbRead.c b/source/dnode/vnode/src/tsdb/tsdbRead.c
index 7787551345a154742f210e35b9343cfac15fc430..3eaa00f0621478d2177183144db704c7128f2f61 100644
--- a/source/dnode/vnode/src/tsdb/tsdbRead.c
+++ b/source/dnode/vnode/src/tsdb/tsdbRead.c
@@ -2112,8 +2112,8 @@ static bool isValidFileBlockRow(SBlockData* pBlockData, SFileBlockDumpInfo* pDum
 
 static bool initLastBlockReader(SLastBlockReader* pLBlockReader, STableBlockScanInfo* pScanInfo, STsdbReader* pReader) {
   // the last block reader has been initialized for this table.
-  if (pLBlockReader->uid == pScanInfo->uid && hasDataInLastBlock(pLBlockReader)) {
-    return true;
+  if (pLBlockReader->uid == pScanInfo->uid) {
+    return hasDataInLastBlock(pLBlockReader);
   }
 
   if (pLBlockReader->uid != 0) {
@@ -2246,6 +2246,9 @@ static int32_t buildComposedDataBlock(STsdbReader* pReader) {
       if (pReader->order == TSDB_ORDER_ASC ||
           (pReader->order == TSDB_ORDER_DESC && (!hasDataInLastBlock(pLastBlockReader)))) {
         copyBlockDataToSDataBlock(pReader, pBlockScanInfo);
+
+        // record the last key value
+        pBlockScanInfo->lastKey = ASCENDING_TRAVERSE(pReader->order)? pBlock->maxKey.ts:pBlock->minKey.ts;
         goto _end;
       }
     }
@@ -2637,12 +2640,10 @@ static int32_t doBuildDataBlock(STsdbReader* pReader) {
       pInfo->window = (STimeWindow){.skey = pBlock->minKey.ts, .ekey = pBlock->maxKey.ts};
       setComposedBlockFlag(pReader, false);
       setBlockAllDumped(&pStatus->fBlockDumpInfo, pBlock->maxKey.ts, pReader->order);
-    }
-  }
 
-  if (code == TSDB_CODE_SUCCESS) {
-    STimeWindow* pWin = &pReader->pResBlock->info.window;
-    pScanInfo->lastKey = ASCENDING_TRAVERSE(pReader->order)? pWin->ekey:pWin->skey;
+      // update the last key for the corresponding table
+      pScanInfo->lastKey = ASCENDING_TRAVERSE(pReader->order)? pInfo->window.ekey:pInfo->window.skey;
+    }
   }
 
   return code;
diff --git a/tests/system-test/1-insert/delete_data.py b/tests/system-test/1-insert/delete_data.py
index d935a08133dd3f76f0b5f2ecdead19e95a12b2e2..95f7649ba1fd6c7490b7cc2d48b628c2dc4cf92a 100644
--- a/tests/system-test/1-insert/delete_data.py
+++ b/tests/system-test/1-insert/delete_data.py
@@ -25,7 +25,7 @@ from util.sqlset import TDSetSql
 class TDTestCase:
     def init(self, conn, logSql, replicaVar=1):
         tdLog.debug("start to execute %s" % __file__)
-        tdSql.init(conn.cursor())
+        tdSql.init(conn.cursor(), True)
         self.dbname = 'db_test'
         self.setsql = TDSetSql()
         self.stbname = 'stb'