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Further cleanups of indexqual processing: simplify control

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logic in indxpath.c, avoid generation of redundant indexscan paths for the
same relation and index.
This commit is contained in:
Tom Lane
1999-07-30 04:07:25 +00:00
parent 037cac7ca6
commit 04578a9180
3 changed files with 122 additions and 154 deletions
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30
src/backend/optimizer/util/pathnode.c
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@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/pathnode.c,v 1.50 1999/07/30 00:56:17 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/pathnode.c,v 1.51 1999/07/30 04:07:25 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -300,23 +300,20 @@ create_seqscan_path(RelOptInfo *rel)
/*
* create_index_path
* Creates a single path node for an index scan.
* Creates a path node for an index scan.
*
* 'rel' is the parent rel
* 'index' is the pathnode for the index on 'rel'
* 'restriction_clauses' is a list of restriction clause nodes.
* 'is_join_scan' is a flag indicating whether or not the index is being
* considered because of its sort order.
* 'index' is an index on 'rel'
* 'restriction_clauses' is a list of RestrictInfo nodes
* to be used as index qual conditions in the scan.
*
* Returns the new path node.
*
*/
IndexPath *
create_index_path(Query *root,
RelOptInfo *rel,
RelOptInfo *index,
List *restriction_clauses,
bool is_join_scan)
List *restriction_clauses)
{
IndexPath *pathnode = makeNode(IndexPath);
@ -361,20 +358,11 @@ create_index_path(Query *root,
else
pathnode->path.pathkeys = NULL;
if (is_join_scan || restriction_clauses == NULL)
if (restriction_clauses == NIL)
{
/*
* Indices used for joins or sorting result nodes don't restrict
* the result at all, they simply order it, so compute the scan
* cost accordingly -- use a selectivity of 1.0.
*
* is the statement above really true? what about IndexScan as the
* inner of a join?
*
* I think it's OK --- this routine is only used to make index paths
* for mergejoins and sorts. Index paths used as the inner side of
* a nestloop join do provide restriction, but they are not made
* with this code. See index_innerjoin() in indxpath.c.
* We have no restriction clauses, so compute scan cost using
* selectivity of 1.0.
*/
pathnode->path.path_cost = cost_index(lfirsti(index->relids),
index->pages,