From 01d790d701974089b1208ecdccaefc75d5f08878 Mon Sep 17 00:00:00 2001
From: Xiaoyu Wang <xiaoyuwang@taosdata.com>
Date: Wed, 26 Oct 2022 17:31:43 +0800
Subject: [PATCH] fix: push down limit

---
 source/libs/planner/src/planSpliter.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/source/libs/planner/src/planSpliter.c b/source/libs/planner/src/planSpliter.c
index 62c7eaef55..59707db574 100644
--- a/source/libs/planner/src/planSpliter.c
+++ b/source/libs/planner/src/planSpliter.c
@@ -97,6 +97,7 @@ static int32_t splCreateExchangeNode(SSplitContext* pCxt, SLogicNode* pChild, SE
     if (NULL == pExchange->node.pLimit) {
       return TSDB_CODE_OUT_OF_MEMORY;
     }
+    ((SLimitNode*)pChild->pLimit)->limit += ((SLimitNode*)pChild->pLimit)->offset;
     ((SLimitNode*)pChild->pLimit)->offset = 0;
   }
 
@@ -470,6 +471,12 @@ static int32_t stbSplCreateMergeNode(SSplitContext* pCxt, SLogicSubplan* pSubpla
   if (NULL == pMerge->node.pTargets || NULL == pMerge->pInputs) {
     code = TSDB_CODE_OUT_OF_MEMORY;
   }
+  if (TSDB_CODE_SUCCESS == code && NULL != pSplitNode->pLimit) {
+    pMerge->node.pLimit = nodesCloneNode(pSplitNode->pLimit);
+    if (NULL == pMerge->node.pLimit) {
+      code = TSDB_CODE_OUT_OF_MEMORY;
+    }
+  }
   if (TSDB_CODE_SUCCESS == code) {
     if (NULL == pSubplan) {
       code = nodesListMakeAppend(&pSplitNode->pChildren, (SNode*)pMerge);
@@ -934,6 +941,7 @@ static int32_t stbSplSplitScanNodeWithoutPartTags(SSplitContext* pCxt, SStableSp
       if (NULL == pSplitNode->pLimit) {
         return TSDB_CODE_OUT_OF_MEMORY;
       }
+      ((SLimitNode*)pInfo->pSplitNode->pLimit)->limit += ((SLimitNode*)pInfo->pSplitNode->pLimit)->offset;
       ((SLimitNode*)pInfo->pSplitNode->pLimit)->offset = 0;
     }
   }
@@ -1021,6 +1029,10 @@ static int32_t stbSplSplitMergeScanNode(SSplitContext* pCxt, SLogicSubplan* pSub
   SNodeList*  pMergeKeys = NULL;
   int32_t     code = stbSplCreateMergeScanNode(pScan, &pMergeScan, &pMergeKeys);
   if (TSDB_CODE_SUCCESS == code) {
+    if (NULL != pMergeScan->pLimit) {
+      ((SLimitNode*)pMergeScan->pLimit)->limit += ((SLimitNode*)pMergeScan->pLimit)->offset;
+      ((SLimitNode*)pMergeScan->pLimit)->offset = 0;
+    }
     code = stbSplCreateMergeNode(pCxt, pSubplan, (SLogicNode*)pScan, pMergeKeys, pMergeScan, groupSort);
   }
   if (TSDB_CODE_SUCCESS == code) {