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Adjust indexscan planning logic to keep RestrictInfo nodes associated

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with index qual clauses in the Path representation.  This saves a little
work during createplan and (probably more importantly) allows reuse of
cached selectivity estimates during indexscan planning.  Also fix latent
bug: wrong plan would have been generated for a 'special operator' used
in a nestloop-inner-indexscan join qual, because the special operator
would not have gotten into the list of quals to recheck.  This bug is
only latent because at present the special-operator code could never
trigger on a join qual, but sooner or later someone will want to do it.
This commit is contained in:
Tom Lane
2004-01-05 23:39:54 +00:00
parent 5d472f6464
commit fa559a86ee
11 changed files with 400 additions and 188 deletions
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28
src/backend/utils/adt/selfuncs.c
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@ -15,7 +15,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.152 2003/12/29 22:22:45 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.153 2004/01/05 23:39:54 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -94,6 +94,7 @@
#include "optimizer/paths.h"
#include "optimizer/plancat.h"
#include "optimizer/prep.h"
#include "optimizer/restrictinfo.h"
#include "optimizer/tlist.h"
#include "optimizer/var.h"
#include "parser/parse_expr.h"
@ -3896,13 +3897,13 @@ genericcostestimate(Query *root, RelOptInfo *rel,
double numIndexTuples;
double numIndexPages;
QualCost index_qual_cost;
List *selectivityQuals = indexQuals;
List *selectivityQuals;
/*
* If the index is partial, AND the index predicate with the
* explicitly given indexquals to produce a more accurate idea of the
* index selectivity. This may produce redundant clauses. We can get
* rid of exact duplicates by using set_union(). We expect that most
* index selectivity. This may produce redundant clauses. We get rid
* of exact duplicates in the code below. We expect that most
* cases of partial redundancy (such as "x < 4" from the qual and
* "x < 5" from the predicate) will be recognized and handled correctly
* by clauselist_selectivity(). This assumption is somewhat fragile,
@ -3913,10 +3914,25 @@ genericcostestimate(Query *root, RelOptInfo *rel,
* necessarily a bad thing. But it'd be nice to do better someday.
*
* Note that index->indpred and indexQuals are both in implicit-AND form,
* so ANDing them together just takes merging the lists.
* so ANDing them together just takes merging the lists. However,
* eliminating duplicates is a bit trickier because indexQuals contains
* RestrictInfo nodes and the indpred does not. It is okay to pass a
* mixed list to clauselist_selectivity, but we have to work a bit to
* generate a list without logical duplicates. (We could just set_union
* indpred and strippedQuals, but then we'd not get caching of per-qual
* selectivity estimates.)
*/
if (index->indpred != NIL)
selectivityQuals = set_union(index->indpred, indexQuals);
{
List *strippedQuals;
List *predExtraQuals;
strippedQuals = get_actual_clauses(indexQuals);
predExtraQuals = set_difference(index->indpred, strippedQuals);
selectivityQuals = nconc(predExtraQuals, indexQuals);
}
else
selectivityQuals = indexQuals;
/* Estimate the fraction of main-table tuples that will be visited */
*indexSelectivity = clauselist_selectivity(root, selectivityQuals,