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Change EXPLAIN output so that subplans and initplans (particularly CTEs)

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are individually labeled, rather than just grouped under an "InitPlan"
or "SubPlan" heading.  This in turn makes it possible for decompilation of
a subplan reference to usefully identify which subplan it's referencing.
I also made InitPlans identify which parameter symbol(s) they compute,
so that references to those parameters elsewhere in the plan tree can
be connected to the initplan that will be executed.  Per a gripe from
Robert Haas about EXPLAIN output of a WITH query being inadequate,
plus some longstanding pet peeves of my own.
This commit is contained in:
Tom Lane
2009-04-05 19:59:40 +00:00
parent 329a5322e9
commit fbcce08046
7 changed files with 82 additions and 22 deletions
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36
src/backend/utils/adt/ruleutils.c
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@@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.296 2009/02/25 18:00:01 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.297 2009/04/05 19:59:40 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -4404,20 +4404,42 @@ get_rule_expr(Node *node, deparse_context *context,
case T_SubPlan:
{
SubPlan *subplan = (SubPlan *) node;
/*
* We cannot see an already-planned subplan in rule deparsing,
* only while EXPLAINing a query plan. For now, just punt.
* only while EXPLAINing a query plan. We don't try to
* reconstruct the original SQL, just reference the subplan
* that appears elsewhere in EXPLAIN's result.
*/
if (((SubPlan *) node)->useHashTable)
appendStringInfo(buf, "(hashed subplan)");
if (subplan->useHashTable)
appendStringInfo(buf, "(hashed %s)", subplan->plan_name);
else
appendStringInfo(buf, "(subplan)");
appendStringInfo(buf, "(%s)", subplan->plan_name);
}
break;
case T_AlternativeSubPlan:
/* As above, just punt */
appendStringInfo(buf, "(alternative subplans)");
{
AlternativeSubPlan *asplan = (AlternativeSubPlan *) node;
ListCell *lc;
/* As above, this can only happen during EXPLAIN */
appendStringInfo(buf, "(alternatives: ");
foreach(lc, asplan->subplans)
{
SubPlan *splan = (SubPlan *) lfirst(lc);
Assert(IsA(splan, SubPlan));
if (splan->useHashTable)
appendStringInfo(buf, "hashed %s", splan->plan_name);
else
appendStringInfo(buf, "%s", splan->plan_name);
if (lnext(lc))
appendStringInfo(buf, " or ");
}
appendStringInfo(buf, ")");
}
break;
case T_FieldSelect: