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Allow the planner to collapse explicit inner JOINs together, rather than

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necessarily following the JOIN syntax to develop the query plan.  The old
behavior is still available by setting GUC variable JOIN_COLLAPSE_LIMIT
to 1.  Also create a GUC variable FROM_COLLAPSE_LIMIT to control the
similar decision about when to collapse sub-SELECT lists into their parent
lists.  (This behavior existed already, but the limit was always
GEQO_THRESHOLD/2; now it's separately adjustable.)
This commit is contained in:
Tom Lane
2003-01-25 23:10:30 +00:00
parent 15ab7a8720
commit 9f5f212475
12 changed files with 1035 additions and 873 deletions
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18
src/backend/optimizer/plan/planner.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.141 2003/01/20 18:54:52 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.142 2003/01/25 23:10:27 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -166,12 +166,6 @@ subquery_planner(Query *parse, double tuple_fraction)
parse->jointree = (FromExpr *)
pull_up_subqueries(parse, (Node *) parse->jointree, false);
/*
* If so, we may have created opportunities to simplify the jointree.
*/
parse->jointree = (FromExpr *)
preprocess_jointree(parse, (Node *) parse->jointree);
/*
* Detect whether any rangetable entries are RTE_JOIN kind; if not,
* we can avoid the expense of doing flatten_join_alias_vars().
@ -246,6 +240,16 @@ subquery_planner(Query *parse, double tuple_fraction)
}
parse->havingQual = (Node *) newHaving;
/*
* See if we can simplify the jointree; opportunities for this may come
* from having pulled up subqueries, or from flattening explicit JOIN
* syntax. We must do this after flattening JOIN alias variables, since
* eliminating explicit JOIN nodes from the jointree will cause
* get_relids_for_join() to fail.
*/
parse->jointree = (FromExpr *)
preprocess_jointree(parse, (Node *) parse->jointree);
/*
* Do the main planning. If we have an inherited target relation,
* that needs special processing, else go straight to