From 8bdc2bf030acae0bdac98c645a3c80f205e7e10a Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Mon, 25 Sep 2000 18:14:55 +0000
Subject: Use variable aliases, if supplied, rather than real column names in
 complaints about ungrouped variables.  This is for consistency with behavior
 elsewhere, notably the fact that the relname is reported as an alias in these
 same complaints.  Also, it'll work with subselect- in-FROM where old code
 didn't.

---
 src/backend/parser/parse_relation.c | 39 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 38 insertions(+), 1 deletion(-)

(limited to 'src/backend/parser/parse_relation.c')

diff --git a/src/backend/parser/parse_relation.c b/src/backend/parser/parse_relation.c
index 491cbc5ef0..baae0a578c 100644
--- a/src/backend/parser/parse_relation.c
+++ b/src/backend/parser/parse_relation.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_relation.c,v 1.47 2000/09/12 21:07:02 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_relation.c,v 1.48 2000/09/25 18:14:54 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -713,6 +713,43 @@ expandNamesVars(ParseState *pstate, List *names, List *vars)
 	return te_list;
 }
 
+/* ----------
+ * get_rte_attribute_name
+ *		Get an attribute name from a RangeTblEntry
+ *
+ * This is unlike get_attname() because we use aliases if available.
+ * In particular, it will work on an RTE for a subselect, whereas
+ * get_attname() only works on real relations.
+ * ----------
+ */
+char *
+get_rte_attribute_name(RangeTblEntry *rte, AttrNumber attnum)
+{
+	char	   *attname;
+
+	/*
+	 * If there is an alias, use it
+	 */
+	if (attnum > 0 && attnum <= length(rte->eref->attrs))
+		return strVal(nth(attnum-1, rte->eref->attrs));
+	/*
+	 * Can get here for a system attribute (which never has an alias),
+	 * or if alias name list is too short (which probably can't happen
+	 * anymore).  Neither of these cases is valid for a subselect RTE.
+	 */
+	if (rte->relid == InvalidOid)
+		elog(ERROR, "Invalid attnum %d for rangetable entry %s",
+			 attnum, rte->eref->relname);
+	/*
+	 * Use the real name of the table's column
+	 */
+	attname = get_attname(rte->relid, attnum);
+	if (attname == NULL)
+		elog(ERROR, "cache lookup of attribute %d in relation %u failed",
+			 attnum, rte->relid);
+	return attname;
+}
+
 /*
  *	given relation and att name, return id of variable
  *
-- 
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