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Rework join-removal logic as per recent discussion. In particular this

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fixes things so that it works for cases where nested removals are possible.
The overhead of the optimization should be significantly less, as well.
This commit is contained in:
Tom Lane
2010-03-28 22:59:34 +00:00
parent a760893dbd
commit b78f6264eb
17 changed files with 585 additions and 317 deletions
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31
src/backend/optimizer/util/placeholder.c
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@@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/util/placeholder.c,v 1.6 2010/01/02 16:57:48 momjian Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/util/placeholder.c,v 1.7 2010/03/28 22:59:33 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -168,18 +168,27 @@ fix_placeholder_eval_levels(PlannerInfo *root)
list_free(vars);
}
}
}
/*
* Now, if any placeholder can be computed at a base rel and is needed
* above it, add it to that rel's targetlist. (This is essentially the
* same logic as in add_placeholders_to_joinrel, but we can't do that part
* until joinrels are formed.) We have to do this as a separate step
* because the ph_needed values aren't stable until the previous loop
* finishes.
*/
foreach(lc1, root->placeholder_list)
/*
* add_placeholders_to_base_rels
* Add any required PlaceHolderVars to base rels' targetlists.
*
* If any placeholder can be computed at a base rel and is needed above it,
* add it to that rel's targetlist. We have to do this separately from
* fix_placeholder_eval_levels() because join removal happens in between,
* and can change the ph_eval_at sets. There is essentially the same logic
* in add_placeholders_to_joinrel, but we can't do that part until joinrels
* are formed.
*/
void
add_placeholders_to_base_rels(PlannerInfo *root)
{
ListCell *lc;
foreach(lc, root->placeholder_list)
{
PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(lc1);
PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(lc);
Relids eval_at = phinfo->ph_eval_at;
if (bms_membership(eval_at) == BMS_SINGLETON)