Modified files for MERGE

1 files changed, 40 insertions, 5 deletions

diff --git a/src/backend/parser/parse_clause.c b/src/backend/parser/parse_clause.c
index 3a02307bd99..3cb761b4ed0 100644
--- a/src/backend/parser/parse_clause.c
+++ b/src/backend/parser/parse_clause.c
@@ -76,9 +76,6 @@ static RangeTblEntry *transformRangeTableFunc(ParseState *pstate,
 						RangeTableFunc *t);
 static TableSampleClause *transformRangeTableSample(ParseState *pstate,
 						  RangeTableSample *rts);
-static Node *transformFromClauseItem(ParseState *pstate, Node *n,
-						RangeTblEntry **top_rte, int *top_rti,
-						List **namespace);
 static Node *buildMergedJoinVar(ParseState *pstate, JoinType jointype,
 				   Var *l_colvar, Var *r_colvar);
 static ParseNamespaceItem *makeNamespaceItem(RangeTblEntry *rte,
@@ -139,6 +136,7 @@ transformFromClause(ParseState *pstate, List *frmList)
 		n = transformFromClauseItem(pstate, n,
 									&rte,
 									&rtindex,
+									NULL, NULL,
 									&namespace);
 
 		checkNameSpaceConflicts(pstate, pstate->p_namespace, namespace);
@@ -1096,13 +1094,20 @@ getRTEForSpecialRelationTypes(ParseState *pstate, RangeVar *rv)
  *
  * *top_rti: receives the rangetable index of top_rte.  (Ditto.)
  *
+ * *right_rte: receives the RTE corresponding to the right side of the
+ * jointree. Only MERGE really needs to know about this and only MERGE passes a
+ * non-NULL pointer.
+ *
+ * *right_rti: receives the rangetable index of the right_rte.
+ *
  * *namespace: receives a List of ParseNamespaceItems for the RTEs exposed
  * as table/column names by this item.  (The lateral_only flags in these items
  * are indeterminate and should be explicitly set by the caller before use.)
  */
-static Node *
+Node *
 transformFromClauseItem(ParseState *pstate, Node *n,
 						RangeTblEntry **top_rte, int *top_rti,
+						RangeTblEntry **right_rte, int *right_rti,
 						List **namespace)
 {
 	if (IsA(n, RangeVar))
@@ -1194,7 +1199,7 @@ transformFromClauseItem(ParseState *pstate, Node *n,
 
 		/* Recursively transform the contained relation */
 		rel = transformFromClauseItem(pstate, rts->relation,
-									  top_rte, top_rti, namespace);
+									  top_rte, top_rti, NULL, NULL, namespace);
 		/* Currently, grammar could only return a RangeVar as contained rel */
 		rtr = castNode(RangeTblRef, rel);
 		rte = rt_fetch(rtr->rtindex, pstate->p_rtable);
@@ -1222,6 +1227,7 @@ transformFromClauseItem(ParseState *pstate, Node *n,
 		List	   *l_namespace,
 				   *r_namespace,
 				   *my_namespace,
+				   *save_namespace,
 				   *l_colnames,
 				   *r_colnames,
 				   *res_colnames,
@@ -1240,6 +1246,7 @@ transformFromClauseItem(ParseState *pstate, Node *n,
 		j->larg = transformFromClauseItem(pstate, j->larg,
 										  &l_rte,
 										  &l_rtindex,
+										  NULL, NULL,
 										  &l_namespace);
 
 		/*
@@ -1263,12 +1270,34 @@ transformFromClauseItem(ParseState *pstate, Node *n,
 		sv_namespace_length = list_length(pstate->p_namespace);
 		pstate->p_namespace = list_concat(pstate->p_namespace, l_namespace);
 
+		/*
+		 * If we are running MERGE, don't make the other RTEs visible while
+		 * parsing the source relation. It mustn't see them.
+		 *
+		 * Currently, only MERGE passes non-NULL value for right_rte, so we
+		 * can safely deduce if we're running MERGE or not by just looking at
+		 * the right_rte. If that ever changes, we should look at other means
+		 * to find that.
+		 */
+		if (right_rte)
+		{
+			save_namespace = pstate->p_namespace;
+			pstate->p_namespace = NIL;
+		}
+
 		/* And now we can process the RHS */
 		j->rarg = transformFromClauseItem(pstate, j->rarg,
 										  &r_rte,
 										  &r_rtindex,
+										  NULL, NULL,
 										  &r_namespace);
 
+		/*
+		 * And now restore the namespace again so that join-quals can see it.
+		 */
+		if (right_rte)
+			pstate->p_namespace = save_namespace;
+
 		/* Remove the left-side RTEs from the namespace list again */
 		pstate->p_namespace = list_truncate(pstate->p_namespace,
 											sv_namespace_length);
@@ -1295,6 +1324,12 @@ transformFromClauseItem(ParseState *pstate, Node *n,
 		expandRTE(r_rte, r_rtindex, 0, -1, false,
 				  &r_colnames, &r_colvars);
 
+		if (right_rte)
+			*right_rte = r_rte;
+
+		if (right_rti)
+			*right_rti = r_rtindex;
+
 		/*
 		 * Natural join does not explicitly specify columns; must generate
 		 * columns to join. Need to run through the list of columns from each