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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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18
src/backend/optimizer/util/pathnode.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/util/pathnode.c,v 1.136 2007/01/10 18:06:04 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/util/pathnode.c,v 1.137 2007/01/20 20:45:39 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -26,7 +26,6 @@
#include "parser/parse_expr.h"
#include "parser/parse_oper.h"
#include "parser/parsetree.h"
#include "utils/memutils.h"
#include "utils/selfuncs.h"
#include "utils/lsyscache.h"
#include "utils/syscache.h"
@ -747,11 +746,11 @@ create_unique_path(PlannerInfo *root, RelOptInfo *rel, Path *subpath)
return (UniquePath *) rel->cheapest_unique_path;
/*
* We must ensure path struct is allocated in same context as parent rel;
* We must ensure path struct is allocated in main planning context;
* otherwise GEQO memory management causes trouble. (Compare
* best_inner_indexscan().)
*/
oldcontext = MemoryContextSwitchTo(GetMemoryChunkContext(rel));
oldcontext = MemoryContextSwitchTo(root->planner_cxt);
pathnode = makeNode(UniquePath);
@ -1198,11 +1197,6 @@ create_nestloop_path(PlannerInfo *root,
* 'pathkeys' are the path keys of the new join path
* 'mergeclauses' are the RestrictInfo nodes to use as merge clauses
* (this should be a subset of the restrict_clauses list)
* 'mergefamilies' are the btree opfamily OIDs identifying the merge
* ordering for each merge clause
* 'mergestrategies' are the btree operator strategies identifying the merge
* ordering for each merge clause
* 'mergenullsfirst' are the nulls first/last flags for each merge clause
* 'outersortkeys' are the sort varkeys for the outer relation
* 'innersortkeys' are the sort varkeys for the inner relation
*/
@ -1215,9 +1209,6 @@ create_mergejoin_path(PlannerInfo *root,
List *restrict_clauses,
List *pathkeys,
List *mergeclauses,
Oid *mergefamilies,
int *mergestrategies,
bool *mergenullsfirst,
List *outersortkeys,
List *innersortkeys)
{
@ -1258,9 +1249,6 @@ create_mergejoin_path(PlannerInfo *root,
pathnode->jpath.joinrestrictinfo = restrict_clauses;
pathnode->jpath.path.pathkeys = pathkeys;
pathnode->path_mergeclauses = mergeclauses;
pathnode->path_mergeFamilies = mergefamilies;
pathnode->path_mergeStrategies = mergestrategies;
pathnode->path_mergeNullsFirst = mergenullsfirst;
pathnode->outersortkeys = outersortkeys;
pathnode->innersortkeys = innersortkeys;