From b62cc145a0562ea1016ef26d346920ccf01d7ff0 Mon Sep 17 00:00:00 2001
From: zhouxiongjia <719216473@qq.com>
Date: Tue, 15 Jun 2021 20:52:44 +0800
Subject: [PATCH] fix two bugs about ROWNUM: 1. ROWNUM behaves incorrect in the
 partition table 2. if there is aggregate function, ROWNUM can not be rewrite
 to LIMIT

---
 src/gausskernel/optimizer/prep/preprownum.cpp         | 4 ++--
 src/gausskernel/runtime/executor/execAmi.cpp          | 4 +++-
 src/gausskernel/runtime/executor/nodePartIterator.cpp | 1 +
 src/include/nodes/execnodes.h                         | 2 +-
 4 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/gausskernel/optimizer/prep/preprownum.cpp b/src/gausskernel/optimizer/prep/preprownum.cpp
index 431f7332b..cb3b82c59 100644
--- a/src/gausskernel/optimizer/prep/preprownum.cpp
+++ b/src/gausskernel/optimizer/prep/preprownum.cpp
@@ -51,8 +51,8 @@ void preprocess_rownum(PlannerInfo *root, Query *parse)
     if (quals == NULL) {
         return;
     }
-    /* If it includes {order by} or {group by}, can not be rewrited */
-    if ((parse->sortClause != NULL) || (parse->groupClause != NULL)) {
+    /* If it includes aggregation function or {order by} or {group by}, can not be rewrited */
+    if (parse->hasAggs || (parse->sortClause != NULL) || (parse->groupClause != NULL)) {
         return;
     }
     if (parse->limitCount != NULL) {
diff --git a/src/gausskernel/runtime/executor/execAmi.cpp b/src/gausskernel/runtime/executor/execAmi.cpp
index 5d0e4aaa8..12e7d0257 100755
--- a/src/gausskernel/runtime/executor/execAmi.cpp
+++ b/src/gausskernel/runtime/executor/execAmi.cpp
@@ -270,7 +270,9 @@ void ExecReScan(PlanState* node)
     }
 
     /* reset the rownum */
-    node->ps_rownum = 0;
+    if (!node->do_not_reset_rownum) {
+        node->ps_rownum = 0;
+    }
 
     /*
      * If we have changed parameters, propagate that info.
diff --git a/src/gausskernel/runtime/executor/nodePartIterator.cpp b/src/gausskernel/runtime/executor/nodePartIterator.cpp
index 85a1260c8..158bfc77e 100755
--- a/src/gausskernel/runtime/executor/nodePartIterator.cpp
+++ b/src/gausskernel/runtime/executor/nodePartIterator.cpp
@@ -98,6 +98,7 @@ TupleTableSlot* ExecPartIterator(PartIteratorState* node)
     TupleTableSlot* slot = NULL;
     PartIterator* pi_node = (PartIterator*)node->ps.plan;
     EState* state = node->ps.lefttree->state;
+    node->ps.lefttree->do_not_reset_rownum = true;
     bool orig_early_free = state->es_skip_early_free;
 
     PlanState* noden = (PlanState*)node->ps.lefttree;
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index c8602d3ef..fbdef251c 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -1234,7 +1234,7 @@ typedef struct PlanState {
     List* plan_issues;
     bool recursive_reset; /* node already reset? */
     bool qual_is_inited;
-
+    bool do_not_reset_rownum;
     int64 ps_rownum;    /* store current rownum */
 } PlanState;