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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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37
src/backend/optimizer/plan/planner.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.211 2007/01/10 18:06:03 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.212 2007/01/20 20:45:39 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -206,6 +206,8 @@ subquery_planner(Query *parse, double tuple_fraction,
/* Create a PlannerInfo data structure for this subquery */
root = makeNode(PlannerInfo);
root->parse = parse;
root->planner_cxt = CurrentMemoryContext;
root->eq_classes = NIL;
root->in_info_list = NIL;
root->append_rel_list = NIL;
@ -715,9 +717,10 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
* operation's result. We have to do this before overwriting the sort
* key information...
*/
current_pathkeys = make_pathkeys_for_sortclauses(set_sortclauses,
result_plan->targetlist);
current_pathkeys = canonicalize_pathkeys(root, current_pathkeys);
current_pathkeys = make_pathkeys_for_sortclauses(root,
set_sortclauses,
result_plan->targetlist,
true);
/*
* We should not need to call preprocess_targetlist, since we must be
@ -742,9 +745,10 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
/*
* Calculate pathkeys that represent result ordering requirements
*/
sort_pathkeys = make_pathkeys_for_sortclauses(parse->sortClause,
tlist);
sort_pathkeys = canonicalize_pathkeys(root, sort_pathkeys);
sort_pathkeys = make_pathkeys_for_sortclauses(root,
parse->sortClause,
tlist,
true);
}
else
{
@ -778,12 +782,18 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
/*
* Calculate pathkeys that represent grouping/ordering requirements.
* Stash them in PlannerInfo so that query_planner can canonicalize
* them.
* them after EquivalenceClasses have been formed.
*/
root->group_pathkeys =
make_pathkeys_for_sortclauses(parse->groupClause, tlist);
make_pathkeys_for_sortclauses(root,
parse->groupClause,
tlist,
false);
root->sort_pathkeys =
make_pathkeys_for_sortclauses(parse->sortClause, tlist);
make_pathkeys_for_sortclauses(root,
parse->sortClause,
tlist,
false);
/*
* Will need actual number of aggregates for estimating costs.
@ -1069,10 +1079,9 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
{
if (!pathkeys_contained_in(sort_pathkeys, current_pathkeys))
{
result_plan = (Plan *)
make_sort_from_sortclauses(root,
parse->sortClause,
result_plan);
result_plan = (Plan *) make_sort_from_pathkeys(root,
result_plan,
sort_pathkeys);
current_pathkeys = sort_pathkeys;
}
}