database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-15 19:21:59 +03:00
Code Activity

Update comments about clause selectivity estimation.

Browse Source
This commit is contained in:
Tom Lane
1999-07-30 22:34:19 +00:00
parent 44763a2b23
commit 30da344cb1
2 changed files with 27 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
src/backend/optimizer/path/allpaths.c
View File

@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/allpaths.c,v 1.51 1999/07/24 23:21:08 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/allpaths.c,v 1.52 1999/07/30 22:34:17 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -59,6 +59,9 @@ make_one_rel(Query *root, List *rels)
if (levels_needed <= 0)
return NULL;
/*
* Generate access paths for the base rels.
*/
set_base_rel_pathlist(root, rels);
if (levels_needed <= 1)
@ -73,8 +76,10 @@ make_one_rel(Query *root, List *rels)
{
/*
* This means that joins or sorts are required. set selectivities
* of clauses that have not been set by an index.
* This means that joins or sorts are required. Set selectivities
* of any clauses not yet set. (I think that this is redundant;
* set_base_rel_pathlist should have set them all already. But
* a scan to check that they are all set doesn't cost much...)
*/
set_rest_relselec(root, rels);
@ -131,11 +136,15 @@ set_base_rel_pathlist(Query *root, List *rels)
set_cheapest(rel, rel->pathlist);
/*
* if there is a qualification of sequential scan the selec. value
* is not set -- so set it explicitly -- Sunita
/* Set the selectivity estimates for any restriction clauses that
* didn't get set as a byproduct of index-path selectivity estimation
* (see create_index_path()).
*/
set_rest_selec(root, rel->restrictinfo);
/* Calculate the estimated size (post-restrictions) and tuple width
* for this base rel. This uses the restriction clause selectivities.
*/
rel->size = compute_rel_size(rel);
rel->width = compute_rel_width(rel);
}