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Revise handling of index-type-specific indexscan cost estimation, per

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pghackers discussion of 5-Jan-2000.  The amopselect and amopnpages
estimators are gone, and in their place is a per-AM amcostestimate
procedure (linked to from pg_am, not pg_amop).
This commit is contained in:
Tom Lane
2000-01-22 23:50:30 +00:00
parent 78845177bb
commit 71ed7eb494
30 changed files with 502 additions and 1113 deletions
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60
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 1.56 2000/01/09 00:26:37 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/pathnode.c,v 1.57 2000/01/22 23:50:17 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -214,64 +214,26 @@ create_index_path(Query *root,
List *restriction_clauses)
{
IndexPath *pathnode = makeNode(IndexPath);
List *indexquals;
pathnode->path.pathtype = T_IndexScan;
pathnode->path.parent = rel;
pathnode->path.pathkeys = build_index_pathkeys(root, rel, index);
indexquals = get_actual_clauses(restriction_clauses);
/* expand special operators to indexquals the executor can handle */
indexquals = expand_indexqual_conditions(indexquals);
/*
* Note that we are making a pathnode for a single-scan indexscan;
* therefore, both indexid and indexqual should be single-element
* lists. We initialize indexqual to contain one empty sublist,
* representing a single index traversal with no index restriction
* conditions. If we do have restriction conditions to use, they
* will get inserted below.
* We are making a pathnode for a single-scan indexscan; therefore,
* both indexid and indexqual should be single-element lists.
*/
pathnode->indexid = lconsi(index->indexoid, NIL);
pathnode->indexqual = lcons(NIL, NIL);
pathnode->indexqual = lcons(indexquals, NIL);
pathnode->joinrelids = NIL; /* no join clauses here */
if (restriction_clauses == NIL)
{
/*
* We have no restriction clauses, so compute scan cost using
* selectivity of 1.0.
*/
pathnode->path.path_cost = cost_index(rel, index,
index->pages,
(Selectivity) 1.0,
false);
}
else
{
/*
* Compute scan cost for the case when 'index' is used with
* restriction clause(s). Also, place indexqual in path node.
*/
List *indexquals;
long npages;
Selectivity selec;
indexquals = get_actual_clauses(restriction_clauses);
/* expand special operators to indexquals the executor can handle */
indexquals = expand_indexqual_conditions(indexquals);
/* Insert qual list into 1st sublist of pathnode->indexqual;
* we already made the cons cell above, no point in wasting it...
*/
lfirst(pathnode->indexqual) = indexquals;
index_selectivity(root,
rel,
index,
indexquals,
&npages,
&selec);
pathnode->path.path_cost = cost_index(rel, index,
npages, selec,
false);
}
pathnode->path.path_cost = cost_index(root, rel, index, indexquals,
false);
return pathnode;
}