From ce5b24abedd3db058c832aabb19940935b2903ae Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 24 May 2007 18:58:42 +0000
Subject: [PATCH] Remove ruleutils.c's use of varnoold/varoattno as a shortcut
for determining what a Var node refers to. This is no longer necessary
because the new flat-range-table representation of plan trees makes it
relatively easy to dig down through child plan levels to find the original
reference; and to keep doing it that way, we'd have to store joinaliasvars
lists in flattened RTEs, as demonstrated by bug report from Leszek Trenkner.
This change makes varnoold/varoattno truly just debug aids, which wasn't
quite the case before. Perhaps we should drop them, or only have them in
assert-enabled builds?
---
src/backend/utils/adt/ruleutils.c | 36 +++++++++++++++++--------------
1 file changed, 20 insertions(+), 16 deletions(-)
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 46cf1dd45af..d5de627df1b 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.257 2007/03/27 23:21:10 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.258 2007/05/24 18:58:42 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -2598,20 +2598,14 @@ get_variable(Var *var, int levelsup, bool showstar, deparse_context *context)
/*
* Try to find the relevant RTE in this rtable. In a plan tree, it's
- * likely that varno is OUTER or INNER, in which case we try to use
- * varnoold instead. If the Var references an expression computed by a
- * subplan, varnoold will be 0, and we must dig down into the subplans.
+ * likely that varno is OUTER or INNER, in which case we must dig down
+ * into the subplans.
*/
if (var->varno >= 1 && var->varno <= list_length(dpns->rtable))
{
rte = rt_fetch(var->varno, dpns->rtable);
attnum = var->varattno;
}
- else if (var->varnoold >= 1 && var->varnoold <= list_length(dpns->rtable))
- {
- rte = rt_fetch(var->varnoold, dpns->rtable);
- attnum = var->varoattno;
- }
else if (var->varno == OUTER && dpns->outer_plan)
{
TargetEntry *tle;
@@ -2631,9 +2625,11 @@ get_variable(Var *var, int levelsup, bool showstar, deparse_context *context)
* Force parentheses because our caller probably assumed a Var is a
* simple expression.
*/
- appendStringInfoChar(buf, '(');
+ if (!IsA(tle->expr, Var))
+ appendStringInfoChar(buf, '(');
get_rule_expr((Node *) tle->expr, context, true);
- appendStringInfoChar(buf, ')');
+ if (!IsA(tle->expr, Var))
+ appendStringInfoChar(buf, ')');
dpns->outer_plan = save_outer;
dpns->inner_plan = save_inner;
@@ -2658,9 +2654,11 @@ get_variable(Var *var, int levelsup, bool showstar, deparse_context *context)
* Force parentheses because our caller probably assumed a Var is a
* simple expression.
*/
- appendStringInfoChar(buf, '(');
+ if (!IsA(tle->expr, Var))
+ appendStringInfoChar(buf, '(');
get_rule_expr((Node *) tle->expr, context, true);
- appendStringInfoChar(buf, ')');
+ if (!IsA(tle->expr, Var))
+ appendStringInfoChar(buf, ')');
dpns->outer_plan = save_outer;
dpns->inner_plan = save_inner;
@@ -2700,7 +2698,13 @@ get_variable(Var *var, int levelsup, bool showstar, deparse_context *context)
* simple reference, we have to just print the unqualified
* variable name (this can only happen with columns that were
* merged by USING or NATURAL clauses).
+ *
+ * This wouldn't work in decompiling plan trees, because we don't
+ * store joinaliasvars lists after planning; but a plan tree
+ * should never contain a join alias variable.
*/
+ if (rte->joinaliasvars == NIL)
+ elog(ERROR, "cannot decompile join alias var in plan tree");
if (attnum > 0)
{
Var *aliasvar;
@@ -2798,9 +2802,7 @@ get_name_for_var_field(Var *var, int fieldno,
/*
* Try to find the relevant RTE in this rtable. In a plan tree, it's
* likely that varno is OUTER or INNER, in which case we must dig down
- * into the subplans. (We can't shortcut with varnoold here, because
- * it might reference a SUBQUERY RTE; we have to dig down to the
- * SubqueryScan plan level to cope with that. See below.)
+ * into the subplans.
*/
if (var->varno >= 1 && var->varno <= list_length(dpns->rtable))
{
@@ -2963,6 +2965,8 @@ get_name_for_var_field(Var *var, int fieldno,
break;
case RTE_JOIN:
/* Join RTE --- recursively inspect the alias variable */
+ if (rte->joinaliasvars == NIL)
+ elog(ERROR, "cannot decompile join alias var in plan tree");
Assert(attnum > 0 && attnum <= list_length(rte->joinaliasvars));
expr = (Node *) list_nth(rte->joinaliasvars, attnum - 1);
if (IsA(expr, Var))
--
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