Get rid of adjust_appendrel_attr_needed(), which has been broken ever since

we extended the appendrel mechanism to support UNION ALL optimization.  The
reason nobody noticed was that we are not actually using attr_needed data for
appendrel children; hence it seems more reasonable to rip it out than fix it.
Back-patch to 8.2 because an Assert failure is possible in corner cases.
Per examination of an example from Jim Nasby.

In HEAD, also get rid of AppendRelInfo.col_mappings, which is quite inadequate
to represent UNION ALL situations; depend entirely on translated_vars instead.

1 files changed, 12 insertions, 17 deletions

diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c
index b15a0e5dd40..b5882a5771a 100644
--- a/src/backend/optimizer/prep/prepjointree.c
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -16,7 +16,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepjointree.c,v 1.58 2008/10/22 20:17:52 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepjointree.c,v 1.59 2008/11/11 18:13:32 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -54,9 +54,8 @@ static Node *pull_up_simple_union_all(PlannerInfo *root, Node *jtnode,
 static void pull_up_union_leaf_queries(Node *setOp, PlannerInfo *root,
 						  int parentRTindex, Query *setOpQuery,
 						  int childRToffset);
-static void make_setop_translation_lists(Query *query,
-							 Index newvarno,
-							 List **col_mappings, List **translated_vars);
+static void make_setop_translation_list(Query *query, Index newvarno,
+							 List **translated_vars);
 static bool is_simple_subquery(Query *subquery);
 static bool is_simple_union_all(Query *subquery);
 static bool is_simple_union_all_recurse(Node *setOp, Query *setOpQuery,
@@ -839,9 +838,8 @@ pull_up_union_leaf_queries(Node *setOp, PlannerInfo *root, int parentRTindex,
 		appinfo->child_relid = childRTindex;
 		appinfo->parent_reltype = InvalidOid;
 		appinfo->child_reltype = InvalidOid;
-		make_setop_translation_lists(setOpQuery, childRTindex,
-									 &appinfo->col_mappings,
-									 &appinfo->translated_vars);
+		make_setop_translation_list(setOpQuery, childRTindex,
+									&appinfo->translated_vars);
 		appinfo->parent_reloid = InvalidOid;
 		root->append_rel_list = lappend(root->append_rel_list, appinfo);
 
@@ -874,17 +872,16 @@ pull_up_union_leaf_queries(Node *setOp, PlannerInfo *root, int parentRTindex,
 }
 
 /*
- * make_setop_translation_lists
- *	  Build the lists of translations from parent Vars to child Vars for
- *	  a UNION ALL member.  We need both a column number mapping list
- *	  and a list of Vars representing the child columns.
+ * make_setop_translation_list
+ *	  Build the list of translations from parent Vars to child Vars for
+ *	  a UNION ALL member.  (At this point it's just a simple list of
+ *	  referencing Vars, but if we succeed in pulling up the member
+ *	  subquery, the Vars will get replaced by pulled-up expressions.)
  */
 static void
-make_setop_translation_lists(Query *query,
-							 Index newvarno,
-							 List **col_mappings, List **translated_vars)
+make_setop_translation_list(Query *query, Index newvarno,
+							List **translated_vars)
 {
-	List	   *numbers = NIL;
 	List	   *vars = NIL;
 	ListCell   *l;
 
@@ -895,7 +892,6 @@ make_setop_translation_lists(Query *query,
 		if (tle->resjunk)
 			continue;
 
-		numbers = lappend_int(numbers, tle->resno);
 		vars = lappend(vars, makeVar(newvarno,
 									 tle->resno,
 									 exprType((Node *) tle->expr),
@@ -903,7 +899,6 @@ make_setop_translation_lists(Query *query,
 									 0));
 	}
 
-	*col_mappings = numbers;
 	*translated_vars = vars;
 }