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Further cleanup for OR-of-AND WHERE-clauses. orindxpath can now handle

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extracting from an AND subclause just those opclauses that are relevant
for a particular index.  For example, we can now consider using an index
on x to process WHERE (x = 1 AND y = 2) OR (x = 2 AND y = 4) OR ...
This commit is contained in:
Tom Lane
2000-02-05 18:26:09 +00:00
parent dd14cd63be
commit 78296c2797
3 changed files with 102 additions and 62 deletions
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42
src/backend/optimizer/path/orindxpath.c
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@ -8,15 +8,13 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/orindxpath.c,v 1.35 2000/01/26 05:56:34 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/orindxpath.c,v 1.36 2000/02/05 18:26:09 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/clauses.h"
#include "optimizer/cost.h"
@ -33,7 +31,8 @@ static void best_or_subclause_indices(Query *root, RelOptInfo *rel,
List **indexids,
Cost *cost);
static void best_or_subclause_index(Query *root, RelOptInfo *rel,
List *indexqual, List *indices,
Expr *subclause, List *indices,
List **retIndexQual,
Oid *retIndexid,
Cost *retCost);
@ -43,7 +42,7 @@ static void best_or_subclause_index(Query *root, RelOptInfo *rel,
* Creates index paths for indices that match 'or' clauses.
* create_index_paths() must already have been called.
*
* 'rel' is the relation entry for which the paths are to be defined on
* 'rel' is the relation entry for which the paths are to be created
* 'clauses' is the list of available restriction clause nodes
*
* Returns a list of index path nodes.
@ -164,21 +163,16 @@ best_or_subclause_indices(Query *root,
foreach(slist, subclauses)
{
Expr *subclause = lfirst(slist);
List *indexqual;
List *best_indexqual;
Oid best_indexid;
Cost best_cost;
/* Convert this 'or' subclause to an indexqual list */
indexqual = make_ands_implicit(subclause);
/* expand special operators to indexquals the executor can handle */
indexqual = expand_indexqual_conditions(indexqual);
best_or_subclause_index(root, rel, indexqual, lfirst(indices),
&best_indexid, &best_cost);
best_or_subclause_index(root, rel, subclause, lfirst(indices),
&best_indexqual, &best_indexid, &best_cost);
Assert(best_indexid != InvalidOid);
*indexquals = lappend(*indexquals, indexqual);
*indexquals = lappend(*indexquals, best_indexqual);
*indexids = lappendi(*indexids, best_indexid);
*cost += best_cost;
@ -193,41 +187,49 @@ best_or_subclause_indices(Query *root,
* the least expensive.
*
* 'rel' is the node of the relation on which the index is defined
* 'indexqual' is the indexqual list derived from the subclause
* 'subclause' is the OR subclause being considered
* 'indices' is a list of IndexOptInfo nodes that match the subclause
* '*retIndexQual' gets a list of the indexqual conditions for the best index
* '*retIndexid' gets the OID of the best index
* '*retCost' gets the cost of a scan with that index
*/
static void
best_or_subclause_index(Query *root,
RelOptInfo *rel,
List *indexqual,
Expr *subclause,
List *indices,
List **retIndexQual, /* return value */
Oid *retIndexid, /* return value */
Cost *retCost) /* return value */
{
bool first_run = true;
bool first_time = true;
List *ilist;
/* if we don't match anything, return zeros */
*retIndexQual = NIL;
*retIndexid = InvalidOid;
*retCost = 0.0;
foreach(ilist, indices)
{
IndexOptInfo *index = (IndexOptInfo *) lfirst(ilist);
List *indexqual;
Cost subcost;
Assert(IsA(index, IndexOptInfo));
/* Convert this 'or' subclause to an indexqual list */
indexqual = extract_or_indexqual_conditions(rel, index, subclause);
subcost = cost_index(root, rel, index, indexqual,
false);
if (first_run || subcost < *retCost)
if (first_time || subcost < *retCost)
{
*retIndexQual = indexqual;
*retIndexid = index->indexoid;
*retCost = subcost;
first_run = false;
first_time = false;
}
}
}