!1031 fix two bugs about ROWNUM

Merge pull request !1031 from 周雄佳/davidzhou

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) {

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.

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;

src/include/nodes/execnodes.h

@@ -1238,7 +1238,7 @@ 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;