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Fix some planner performance problems with large WHERE clauses, by

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introducing new 'FastList' list-construction subroutines to use in
hot spots.  This avoids the O(N^2) behavior of repeated lappend's
by keeping a tail pointer, while not changing behavior by reversing
list order as the lcons() method would do.
This commit is contained in:
Tom Lane
2003-05-28 22:32:50 +00:00
parent 0f3c68aa43
commit 8a6ac83dab
8 changed files with 374 additions and 202 deletions
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15
src/backend/optimizer/path/orindxpath.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/orindxpath.c,v 1.49 2002/12/12 15:49:31 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/orindxpath.c,v 1.50 2003/05/28 22:32:49 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -149,10 +149,12 @@ best_or_subclause_indices(Query *root,
List *indices,
IndexPath *pathnode)
{
FastList infos;
FastList quals;
List *slist;
pathnode->indexinfo = NIL;
pathnode->indexqual = NIL;
FastListInit(&infos);
FastListInit(&quals);
pathnode->path.startup_cost = 0;
pathnode->path.total_cost = 0;
@ -170,14 +172,17 @@ best_or_subclause_indices(Query *root,
Assert(best_indexinfo != NULL);
pathnode->indexinfo = lappend(pathnode->indexinfo, best_indexinfo);
pathnode->indexqual = lappend(pathnode->indexqual, best_indexqual);
FastAppend(&infos, best_indexinfo);
FastAppend(&quals, best_indexqual);
if (slist == subclauses) /* first scan? */
pathnode->path.startup_cost = best_startup_cost;
pathnode->path.total_cost += best_total_cost;
indices = lnext(indices);
}
pathnode->indexinfo = FastListValue(&infos);
pathnode->indexqual = FastListValue(&quals);
}
/*