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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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44
src/backend/optimizer/util/joininfo.c
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/util/joininfo.c,v 1.46 2007/01/05 22:19:32 momjian Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/util/joininfo.c,v 1.47 2007/01/20 20:45:39 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -16,6 +16,7 @@
#include "optimizer/joininfo.h"
#include "optimizer/pathnode.h"
#include "optimizer/paths.h"
/*
@@ -54,6 +55,13 @@ have_relevant_joinclause(PlannerInfo *root,
}
}
/*
* We also need to check the EquivalenceClass data structure, which
* might contain relationships not emitted into the joininfo lists.
*/
if (!result && rel1->has_eclass_joins && rel2->has_eclass_joins)
result = have_relevant_eclass_joinclause(root, rel1, rel2);
/*
* It's possible that the rels correspond to the left and right sides
* of a degenerate outer join, that is, one with no joinclause mentioning
@@ -124,37 +132,3 @@ add_join_clause_to_rels(PlannerInfo *root,
}
bms_free(tmprelids);
}
/*
* remove_join_clause_from_rels
* Delete 'restrictinfo' from all the joininfo lists it is in
*
* This reverses the effect of add_join_clause_to_rels. It's used when we
* discover that a join clause is redundant.
*
* 'restrictinfo' describes the join clause
* 'join_relids' is the list of relations participating in the join clause
* (there must be more than one)
*/
void
remove_join_clause_from_rels(PlannerInfo *root,
RestrictInfo *restrictinfo,
Relids join_relids)
{
Relids tmprelids;
int cur_relid;
tmprelids = bms_copy(join_relids);
while ((cur_relid = bms_first_member(tmprelids)) >= 0)
{
RelOptInfo *rel = find_base_rel(root, cur_relid);
/*
* Remove the restrictinfo from the list. Pointer comparison is
* sufficient.
*/
Assert(list_member_ptr(rel->joininfo, restrictinfo));
rel->joininfo = list_delete_ptr(rel->joininfo, restrictinfo);
}
bms_free(tmprelids);
}