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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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8
src/backend/optimizer/prep/prepunion.c
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@ -22,7 +22,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.135 2007/01/05 22:19:32 momjian Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.136 2007/01/20 20:45:39 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1195,10 +1195,8 @@ adjust_appendrel_attrs_mutator(Node *node, AppendRelInfo *context)
*/
newinfo->eval_cost.startup = -1;
newinfo->this_selec = -1;
newinfo->left_pathkey = NIL;
newinfo->right_pathkey = NIL;
newinfo->left_mergescansel = -1;
newinfo->right_mergescansel = -1;
newinfo->left_ec = NULL;
newinfo->right_ec = NULL;
newinfo->left_bucketsize = -1;
newinfo->right_bucketsize = -1;