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Teach planner how to rearrange join order for some classes of OUTER JOIN.

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Per my recent proposal.  I ended up basing the implementation on the
existing mechanism for enforcing valid join orders of IN joins --- the
rules for valid outer-join orders are somewhat similar.
This commit is contained in:
Tom Lane
2005-12-20 02:30:36 +00:00
parent 1a6aaaa6c4
commit e3b9852728
23 changed files with 969 additions and 722 deletions
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15
src/backend/optimizer/plan/planner.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.195 2005/11/22 18:17:13 momjian Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.196 2005/12/20 02:30:36 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -352,17 +352,6 @@ subquery_planner(Query *parse, double tuple_fraction,
if (root->hasOuterJoins)
reduce_outer_joins(root);
/*
* 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. But it should happen after
* reduce_outer_joins, anyway.
*/
parse->jointree = (FromExpr *)
simplify_jointree(root, (Node *) parse->jointree);
/*
* Do the main planning. If we have an inherited target relation, that
* needs special processing, else go straight to grouping_planner.
@ -567,6 +556,8 @@ inheritance_planner(PlannerInfo *root, List *inheritlist)
adjust_inherited_attrs((Node *) root->in_info_list,
parentRTindex, parentOID,
childRTindex, childOID);
/* There shouldn't be any OJ info to translate, though */
Assert(subroot.oj_info_list == NIL);
/* Generate plan */
subplan = grouping_planner(&subroot, 0.0 /* retrieve all tuples */ );