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Refactor planner's pathkeys data structure to create a separate, explicit

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representation of equivalence classes of variables.  This is an extensive
rewrite, but it brings a number of benefits:
* planner no longer fails in the presence of "incomplete" operator families
that don't offer operators for every possible combination of datatypes.
* avoid generating and then discarding redundant equality clauses.
* remove bogus assumption that derived equalities always use operators
named "=".
* mergejoins can work with a variety of sort orders (e.g., descending) now,
instead of tying each mergejoinable operator to exactly one sort order.
* better recognition of redundant sort columns.
* can make use of equalities appearing underneath an outer join.
This commit is contained in:
Tom Lane
2007-01-20 20:45:41 +00:00
parent 2b7334d487
commit f41803bb39
35 changed files with 3882 additions and 2719 deletions
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12
src/backend/optimizer/path/allpaths.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.156 2007/01/09 02:14:12 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.157 2007/01/20 20:45:38 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -325,6 +325,16 @@ set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
adjust_appendrel_attrs((Node *) rel->joininfo,
appinfo);
/*
* We have to make child entries in the EquivalenceClass data
* structures as well.
*/
if (rel->has_eclass_joins)
{
add_child_rel_equivalences(root, appinfo, rel, childrel);
childrel->has_eclass_joins = true;
}
/*
* Copy the parent's attr_needed data as well, with appropriate
* adjustment of relids and attribute numbers.