diff --git a/source/libs/executor/inc/mergejoin.h b/source/libs/executor/inc/mergejoin.h
index ae3893b965..a25c26a389 100755
--- a/source/libs/executor/inc/mergejoin.h
+++ b/source/libs/executor/inc/mergejoin.h
@@ -19,10 +19,17 @@
 extern "C" {
 #endif
 
+#if 0
 #define MJOIN_DEFAULT_BLK_ROWS_NUM 2 //4096
-#define MJOIN_HJOIN_CART_THRESHOLD 1024 //16
+#define MJOIN_HJOIN_CART_THRESHOLD 16
 #define MJOIN_BLK_SIZE_LIMIT 0 //10485760
 #define MJOIN_ROW_BITMAP_SIZE (2 * 1048576)
+#else
+#define MJOIN_DEFAULT_BLK_ROWS_NUM 4096
+#define MJOIN_HJOIN_CART_THRESHOLD 16
+#define MJOIN_BLK_SIZE_LIMIT 10485760
+#define MJOIN_ROW_BITMAP_SIZE (2 * 1048576)
+#endif
 
 struct SMJoinOperatorInfo;
 
@@ -94,6 +101,7 @@ typedef struct SMJoinTableCtx {
   SMJoinColMap*  finCols;
   
   int32_t        keyNum;
+  int32_t        keyNullSize;
   SMJoinColInfo* keyCols;
   char*          keyBuf;
   char*          keyData;
@@ -212,7 +220,7 @@ typedef struct SMJoinOperatorInfo {
 #define MJOIN_DS_NEED_INIT(_pOp, _tbctx) (MJOIN_DS_REQ_INIT(_pOp) && (!(_tbctx)->dsInitDone))
 #define MJOIN_TB_LOW_BLK(_tbctx) ((_tbctx)->blkNum <= 0 || ((_tbctx)->blkNum == 1 && (_tbctx)->pHeadBlk->cloned))
 
-#define REACH_HJOIN_THRESHOLD(_prb, _bld) ((_prb)->grpTotalRows * (_bld)->grpTotalRows >= MJOIN_HJOIN_CART_THRESHOLD)
+#define REACH_HJOIN_THRESHOLD(_prb, _bld) ((_bld)->grpTotalRows >= MJOIN_HJOIN_CART_THRESHOLD)
 
 #define SET_SAME_TS_GRP_HJOIN(_pair, _octx) ((_pair)->hashJoin = (_octx)->hashCan && REACH_HJOIN_THRESHOLD(_pair))
 
diff --git a/source/libs/executor/src/mergejoinoperator.c b/source/libs/executor/src/mergejoinoperator.c
index 36fa07ea52..4b5cca0ad7 100644
--- a/source/libs/executor/src/mergejoinoperator.c
+++ b/source/libs/executor/src/mergejoinoperator.c
@@ -472,12 +472,18 @@ static int32_t mJoinInitColsInfo(int32_t* colNum, int64_t* rowSize, SMJoinColInf
 }
 
 
-static int32_t mJoinInitKeyColsInfo(SMJoinTableCtx* pTable, SNodeList* pList) {
+static int32_t mJoinInitKeyColsInfo(SMJoinTableCtx* pTable, SNodeList* pList, bool allocKeyBuf) {
   int64_t rowSize = 0;
   MJ_ERR_RET(mJoinInitColsInfo(&pTable->keyNum, &rowSize, &pTable->keyCols, pList));
 
-  if (pTable->keyNum > 1) {
-    pTable->keyBuf = taosMemoryMalloc(rowSize);
+  if (pTable->keyNum > 1 || allocKeyBuf) {
+    if (rowSize > 1) {
+      pTable->keyNullSize = 1;
+    } else {
+      pTable->keyNullSize = 2;
+    }
+
+    pTable->keyBuf = taosMemoryMalloc(TMAX(rowSize, pTable->keyNullSize));
     if (NULL == pTable->keyBuf) {
       return TSDB_CODE_OUT_OF_MEMORY;
     }
@@ -516,7 +522,7 @@ static int32_t mJoinInitTableInfo(SMJoinOperatorInfo* pJoin, SSortMergeJoinPhysi
   pTable->blkId = pDownstream[idx]->resultDataBlockId;
   MJ_ERR_RET(mJoinInitPrimKeyInfo(pTable, (0 == idx) ? pJoinNode->leftPrimSlotId : pJoinNode->rightPrimSlotId));
 
-  MJ_ERR_RET(mJoinInitKeyColsInfo(pTable, (0 == idx) ? pJoinNode->pEqLeft : pJoinNode->pEqRight));
+  MJ_ERR_RET(mJoinInitKeyColsInfo(pTable, (0 == idx) ? pJoinNode->pEqLeft : pJoinNode->pEqRight, JOIN_TYPE_FULL == pJoin->joinType));
   MJ_ERR_RET(mJoinInitColsMap(&pTable->finNum, &pTable->finCols, pTable->blkId, pJoinNode->pTargets));
 
   memcpy(&pTable->inputStat, pStat, sizeof(*pStat));
@@ -870,7 +876,9 @@ int32_t mJoinCreateFullBuildTbHash(SMJoinOperatorInfo* pJoin, SMJoinTableCtx* pT
     int32_t grpRows = GRP_REMAIN_ROWS(pGrp);
     for (int32_t r = 0; r < grpRows; ++r) {
       if (mJoinCopyKeyColsDataToBuf(pTable, pGrp->beginIdx + r, &bufLen)) {
-        continue;
+        *(int16_t *)pTable->keyBuf = 0;
+        pTable->keyData = pTable->keyBuf;
+        bufLen = pTable->keyNullSize;
       }
 
       MJ_ERR_RET(mJoinAddRowToFullHash(pJoin, bufLen, pGrp->blk, pGrp->beginIdx + r));
diff --git a/source/libs/executor/test/joinTests.cpp b/source/libs/executor/test/joinTests.cpp
index aff129edc0..d0691b0467 100755
--- a/source/libs/executor/test/joinTests.cpp
+++ b/source/libs/executor/test/joinTests.cpp
@@ -66,7 +66,7 @@ enum {
 };
 
 #define COL_DISPLAY_WIDTH 18
-#define JT_MAX_LOOP       3000
+#define JT_MAX_LOOP       1000
 
 #define LEFT_BLK_ID       0
 #define RIGHT_BLK_ID      1
@@ -1777,7 +1777,7 @@ void runSingleTest(char* caseName, SJoinTestParam* param) {
   bool contLoop = true;
   
   SSortMergeJoinPhysiNode* pNode = createDummySortMergeJoinPhysiNode(param->joinType, param->subType, param->cond, param->filter, param->asc);    
-  createDummyBlkList(10, 10, 10, 10, 2);
+  createDummyBlkList(10, 10, 10, 10, 3);
   
   while (contLoop) {
     rerunBlockedHere();
@@ -1803,7 +1803,7 @@ void runSingleTest(char* caseName, SJoinTestParam* param) {
 }
 
 void handleCaseEnd() {
-  taosMemoryFree(jtCtx.rightFinMatch);
+  taosMemoryFreeClear(jtCtx.rightFinMatch);
   jtCtx.rightFinMatchNum = 0;
 }
 
@@ -1911,7 +1911,7 @@ TEST(leftOuterJoin, fullCondTest) {
 #endif
 #endif
 
-#if 0
+#if 1
 TEST(fullOuterJoin, noCondTest) {
   SJoinTestParam param;
   char* caseName = "fullOuterJoin:noCondTest";
@@ -1936,7 +1936,7 @@ TEST(fullOuterJoin, noCondTest) {
 }
 #endif
 
-#if 0
+#if 1
 TEST(fullOuterJoin, eqCondTest) {
   SJoinTestParam param;
   char* caseName = "fullOuterJoin:eqCondTest";
diff --git a/tests/script/tsim/join/full_join.sim b/tests/script/tsim/join/full_join.sim
new file mode 100644
index 0000000000..23b198dd5d
--- /dev/null
+++ b/tests/script/tsim/join/full_join.sim
@@ -0,0 +1,188 @@
+sql connect
+sql use test0;
+
+sql select a.col1, b.col1 from sta a full join sta b on a.ts = b.ts and a.ts < '2023-11-17 16:29:02' and b.ts < '2023-11-17 16:29:01' order by a.col1, b.col1;
+if $rows != 10 then
+  return -1
+endi
+if $data00 != 1 then
+  return -1
+endi
+if $data01 != 1 then
+  return -1
+endi
+if $data10 != 1 then
+  return -1
+endi
+if $data11 != 2 then
+  return -1
+endi
+if $data20 != 2 then
+  return -1
+endi
+if $data21 != 1 then
+  return -1
+endi
+if $data30 != 2 then
+  return -1
+endi
+if $data31 != 2 then
+  return -1
+endi
+if $data40 != 3 then
+  return -1
+endi
+if $data41 != NULL then
+  return -1
+endi
+if $data50 != 3 then
+  return -1
+endi
+if $data51 != NULL then
+  return -1
+endi
+if $data60 != 4 then
+  return -1
+endi
+if $data61 != NULL then
+  return -1
+endi
+if $data70 != 5 then
+  return -1
+endi
+if $data71 != NULL then
+  return -1
+endi
+if $data80 != 5 then
+  return -1
+endi
+if $data81 != NULL then
+  return -1
+endi
+if $data90 != 7 then
+  return -1
+endi
+if $data91 != NULL then
+  return -1
+endi
+
+sql select a.col1, b.col1 from sta a full join sta b on a.ts = b.ts where a.ts < '2023-11-17 16:29:02' and b.ts < '2023-11-17 16:29:01' order by a.col1, b.col1;
+if $rows != 4 then
+  return -1
+endi
+if $data00 != 1 then
+  return -1
+endi
+if $data01 != 1 then
+  return -1
+endi
+if $data10 != 1 then
+  return -1
+endi
+if $data11 != 2 then
+  return -1
+endi
+if $data20 != 2 then
+  return -1
+endi
+if $data21 != 1 then
+  return -1
+endi
+if $data30 != 2 then
+  return -1
+endi
+if $data31 != 2 then
+  return -1
+endi
+
+sql select a.col1, b.col1 from sta a full join sta b on a.ts = b.ts;
+if $rows != 12 then
+  return -1
+endi
+
+sql select a.col1, b.col1 from tba1 a full join tba2 b on a.ts = b.ts order by a.col1, b.col1;
+if $rows != 4 then
+  return -1
+endi
+if $data00 != 1 then
+  return -1
+endi
+if $data01 != 2 then
+  return -1
+endi
+if $data10 != 3 then
+  return -1
+endi
+if $data11 != NULL then
+  return -1
+endi
+if $data20 != 4 then
+  return -1
+endi
+if $data21 != 5 then
+  return -1
+endi
+if $data30 != 5 then
+  return -1
+endi
+if $data31 != NULL then
+  return -1
+endi
+
+sql select a.col1, b.col1 from tba2 a full join tba1 b on a.ts = b.ts order by a.col1, b.col1;
+if $rows != 4 then
+  return -1
+endi
+if $data00 != 2 then
+  return -1
+endi
+if $data01 != 1 then
+  return -1
+endi
+if $data10 != 3 then
+  return -1
+endi
+if $data11 != NULL then
+  return -1
+endi
+if $data20 != 5 then
+  return -1
+endi
+if $data21 != 4 then
+  return -1
+endi
+if $data30 != 7 then
+  return -1
+endi
+if $data31 != NULL then
+  return -1
+endi
+
+sql select a.ts, b.ts from tba1 a full join tba2 b on a.ts = b.ts and a.ts < '2023-11-17 16:29:03' and b.ts < '2023-11-17 16:29:03';
+if $rows != 4 then
+  return -1
+endi
+if $data00 != 2 then
+  return -1
+endi
+if $data01 != 1 then
+  return -1
+endi
+if $data10 != 3 then
+  return -1
+endi
+if $data11 != NULL then
+  return -1
+endi
+if $data20 != 5 then
+  return -1
+endi
+if $data21 != 4 then
+  return -1
+endi
+if $data30 != 7 then
+  return -1
+endi
+if $data31 != NULL then
+  return -1
+endi