diff --git a/source/dnode/vnode/src/tsdb/tsdbCacheRead.c b/source/dnode/vnode/src/tsdb/tsdbCacheRead.c
index 417c014b6e..5c09c7663f 100644
--- a/source/dnode/vnode/src/tsdb/tsdbCacheRead.c
+++ b/source/dnode/vnode/src/tsdb/tsdbCacheRead.c
@@ -22,7 +22,6 @@ typedef struct SLastrowReader {
   SVnode*   pVnode;
   STSchema* pSchema;
   uint64_t  uid;
-  //  int32_t*  pSlotIds;
   char**  transferBuf;  // todo remove it soon
   int32_t numOfCols;
   int32_t type;
@@ -31,6 +30,7 @@ typedef struct SLastrowReader {
 } SLastrowReader;
 
 static void saveOneRow(STSRow* pRow, SSDataBlock* pBlock, SLastrowReader* pReader, const int32_t* slotIds) {
+  ASSERT(pReader->numOfCols <= taosArrayGetSize(pBlock->pDataBlock));
   int32_t numOfRows = pBlock->info.rows;
 
   SColVal colVal = {0};
@@ -40,15 +40,17 @@ static void saveOneRow(STSRow* pRow, SSDataBlock* pBlock, SLastrowReader* pReade
     if (slotIds[i] == -1) {
       colDataAppend(pColInfoData, numOfRows, (const char*)&pRow->ts, false);
     } else {
-      tTSRowGetVal(pRow, pReader->pSchema, slotIds[i], &colVal);
+      int32_t slotId = slotIds[i];
+
+      tTSRowGetVal(pRow, pReader->pSchema, slotId, &colVal);
 
       if (IS_VAR_DATA_TYPE(colVal.type)) {
         if (colVal.isNull || colVal.isNone) {
           colDataAppendNULL(pColInfoData, numOfRows);
         } else {
-          varDataSetLen(pReader->transferBuf[i], colVal.value.nData);
-          memcpy(varDataVal(pReader->transferBuf[i]), colVal.value.pData, colVal.value.nData);
-          colDataAppend(pColInfoData, numOfRows, pReader->transferBuf[i], false);
+          varDataSetLen(pReader->transferBuf[slotId], colVal.value.nData);
+          memcpy(varDataVal(pReader->transferBuf[slotId]), colVal.value.pData, colVal.value.nData);
+          colDataAppend(pColInfoData, numOfRows, pReader->transferBuf[slotId], false);
         }
       } else {
         colDataAppend(pColInfoData, numOfRows, (const char*)&colVal.value, colVal.isNull || colVal.isNone);
@@ -68,7 +70,6 @@ int32_t tsdbLastRowReaderOpen(void* pVnode, int32_t type, SArray* pTableIdList,
   p->type = type;
   p->pVnode = pVnode;
   p->numOfCols = numOfCols;
-  p->transferBuf = taosMemoryCalloc(p->numOfCols, POINTER_BYTES);
 
   if (taosArrayGetSize(pTableIdList) == 0) {
     *pReader = p;
@@ -79,7 +80,8 @@ int32_t tsdbLastRowReaderOpen(void* pVnode, int32_t type, SArray* pTableIdList,
   p->pSchema = metaGetTbTSchema(p->pVnode->pMeta, pKeyInfo->uid, -1);
   p->pTableList = pTableIdList;
 
-  for (int32_t i = 0; i < p->numOfCols; ++i) {
+  p->transferBuf = taosMemoryCalloc(p->pSchema->numOfCols, POINTER_BYTES);
+  for (int32_t i = 0; i < p->pSchema->numOfCols; ++i) {
     if (IS_VAR_DATA_TYPE(p->pSchema->columns[i].type)) {
       p->transferBuf[i] = taosMemoryMalloc(p->pSchema->columns[i].bytes);
     }
@@ -92,10 +94,11 @@ int32_t tsdbLastRowReaderOpen(void* pVnode, int32_t type, SArray* pTableIdList,
 int32_t tsdbLastrowReaderClose(void* pReader) {
   SLastrowReader* p = pReader;
 
-  for (int32_t i = 0; i < p->numOfCols; ++i) {
+  for (int32_t i = 0; i < p->pSchema->numOfCols; ++i) {
     taosMemoryFreeClear(p->transferBuf[i]);
   }
 
+  taosMemoryFree(p->pSchema);
   taosMemoryFree(p->transferBuf);
   taosMemoryFree(pReader);
   return TSDB_CODE_SUCCESS;
diff --git a/source/dnode/vnode/src/tsdb/tsdbRead.c b/source/dnode/vnode/src/tsdb/tsdbRead.c
index dc7c54fdc9..e86a14a30f 100644
--- a/source/dnode/vnode/src/tsdb/tsdbRead.c
+++ b/source/dnode/vnode/src/tsdb/tsdbRead.c
@@ -63,10 +63,10 @@ typedef struct SBlockLoadSuppInfo {
 } SBlockLoadSuppInfo;
 
 typedef struct SFilesetIter {
-  int32_t numOfFiles;  // number of total files
-  int32_t index;       // current accessed index in the list
-  SArray* pFileList;   // data file list
-  int32_t order;
+  int32_t          numOfFiles;  // number of total files
+  int32_t          index;       // current accessed index in the list
+  SArray*          pFileList;   // data file list
+  int32_t          order;
 } SFilesetIter;
 
 typedef struct SFileDataBlockInfo {
@@ -302,7 +302,10 @@ static bool filesetIteratorNext(SFilesetIter* pIter, STsdbReader* pReader) {
   STimeWindow win = {0};
 
   while (1) {
-    /*if (pReader->pFileReader != NULL) tsdbDataFReaderClose(&pReader->pFileReader);*/
+//    if (pReader->pFileReader != NULL) {
+//      tsdbDataFReaderClose(&pReader->pFileReader);
+//    }
+
     pReader->status.pCurrentFileset = (SDFileSet*)taosArrayGet(pIter->pFileList, pIter->index);
 
     int32_t code = tsdbDataFReaderOpen(&pReader->pFileReader, pReader->pTsdb, pReader->status.pCurrentFileset);
@@ -2434,6 +2437,7 @@ static int32_t doMergeRowsInFileBlockImpl(SBlockData* pBlockData, int32_t rowInd
                                           SVersionRange* pVerRange, int32_t step) {
   while (pBlockData->aTSKEY[rowIndex] == key && rowIndex < pBlockData->nRow && rowIndex >= 0) {
     if (pBlockData->aVersion[rowIndex] > pVerRange->maxVer || pBlockData->aVersion[rowIndex] < pVerRange->minVer) {
+      rowIndex += step;
       continue;
     }
 
@@ -2832,7 +2836,10 @@ void tsdbReaderClose(STsdbReader* pReader) {
   destroyBlockScanInfo(pReader->status.pTableMap);
   blockDataDestroy(pReader->pResBlock);
 
-  if (pReader->pFileReader != NULL) tsdbDataFReaderClose(&pReader->pFileReader);
+  if (pReader->pFileReader != NULL) {
+    tsdbDataFReaderClose(&pReader->pFileReader);
+  }
+
 #if 0
 //   if (pReader->status.pTableScanInfo != NULL) {
 //     pReader->status.pTableScanInfo = destroyTableCheckInfo(pReader->status.pTableScanInfo);
@@ -3020,6 +3027,7 @@ int32_t tsdbReaderReset(STsdbReader* pReader, SQueryTableDataCond* pCond) {
   memset(pReader->suppInfo.plist, 0, POINTER_BYTES);
 
   pReader->suppInfo.tsColAgg.colId = PRIMARYKEY_TIMESTAMP_COL_ID;
+  tsdbDataFReaderClose(&pReader->pFileReader);
 
   // todo set the correct numOfTables
   int32_t         numOfTables = 1;
diff --git a/source/libs/function/src/builtins.c b/source/libs/function/src/builtins.c
index a735edafab..f1b46aa69b 100644
--- a/source/libs/function/src/builtins.c
+++ b/source/libs/function/src/builtins.c
@@ -2217,7 +2217,7 @@ const SBuiltinFuncDefinition funcMgtBuiltins[] = {
   {
     .name = "last_row",
     .type = FUNCTION_TYPE_LAST_ROW,
-    .classification = FUNC_MGT_AGG_FUNC | FUNC_MGT_MULTI_RES_FUNC | FUNC_MGT_SELECT_FUNC | FUNC_MGT_TIMELINE_FUNC,
+    .classification = FUNC_MGT_AGG_FUNC | FUNC_MGT_MULTI_RES_FUNC | FUNC_MGT_SELECT_FUNC | FUNC_MGT_TIMELINE_FUNC | FUNC_MGT_IMPLICIT_TS_FUNC,
     .translateFunc = translateFirstLast,
     .getEnvFunc   = getFirstLastFuncEnv,
     .initFunc     = functionSetup,
diff --git a/source/libs/function/src/builtinsimpl.c b/source/libs/function/src/builtinsimpl.c
index 0dbf476837..ccf28bfd78 100644
--- a/source/libs/function/src/builtinsimpl.c
+++ b/source/libs/function/src/builtinsimpl.c
@@ -80,8 +80,10 @@ typedef struct STopBotRes {
 } STopBotRes;
 
 typedef struct SFirstLastRes {
-  bool    hasResult;
-  bool    isNull;  // used for last_row function only
+  bool hasResult;
+  // used for last_row function only, isNullRes in SResultRowEntry can not be passed to downstream.So,
+  // this attribute is required
+  bool isNull;
   int32_t bytes;
   char    buf[];
 } SFirstLastRes;
@@ -2948,7 +2950,7 @@ int32_t firstLastFinalize(SqlFunctionCtx* pCtx, SSDataBlock* pBlock) {
   pResInfo->isNullRes = (pResInfo->numOfRes == 0) ? 1 : 0;
 
   SFirstLastRes* pRes = GET_ROWCELL_INTERBUF(pResInfo);
-  colDataAppend(pCol, pBlock->info.rows, pRes->buf, pResInfo->isNullRes);
+  colDataAppend(pCol, pBlock->info.rows, pRes->buf, pRes->isNull||pResInfo->isNullRes);
   // handle selectivity
   STuplePos* pTuplePos = (STuplePos*)(pRes->buf + pRes->bytes + sizeof(TSKEY));
   setSelectivityValue(pCtx, pBlock, pTuplePos, pBlock->info.rows);
@@ -5988,24 +5990,28 @@ int32_t lastrowFunction(SqlFunctionCtx* pCtx) {
 
   int32_t type = pInputCol->info.type;
   int32_t bytes = pInputCol->info.bytes;
+
   pInfo->bytes = bytes;
 
+  // last_row function does not ignore the null value
   for (int32_t i = pInput->numOfRows + pInput->startRowIndex - 1; i >= pInput->startRowIndex; --i) {
-    if (pInputCol->hasNull && colDataIsNull_s(pInputCol, i)) {
-      continue;
-    }
-
     numOfElems++;
 
     char* data = colDataGetData(pInputCol, i);
     TSKEY cts = getRowPTs(pInput->pPTS, i);
     if (pResInfo->numOfRes == 0 || *(TSKEY*)(pInfo->buf + bytes) < cts) {
-      if (IS_VAR_DATA_TYPE(type)) {
-        bytes = varDataTLen(data);
-        pInfo->bytes = bytes;
+
+      if (colDataIsNull_s(pInputCol, i)) {
+        pInfo->isNull = true;
+      } else {
+        if (IS_VAR_DATA_TYPE(type)) {
+          bytes = varDataTLen(data);
+          pInfo->bytes = bytes;
+        }
+
+        memcpy(pInfo->buf, data, bytes);
       }
 
-      memcpy(pInfo->buf, data, bytes);
       *(TSKEY*)(pInfo->buf + bytes) = cts;
 
       pInfo->hasResult = true;
diff --git a/tools/taosws-rs b/tools/taosws-rs
index 6dccac192a..7a94ffab45 160000
--- a/tools/taosws-rs
+++ b/tools/taosws-rs
@@ -1 +1 @@
-Subproject commit 6dccac192a2ae7dd78718ab926201aab5419327a
+Subproject commit 7a94ffab45f08e16f09b3f430fe75d717054adb6