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Back out cleanup patch. Got old version and needs work.

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Neil Conway
This commit is contained in:
Bruce Momjian
2002-06-25 17:58:10 +00:00
parent ed275aea42
commit e2c007046f
13 changed files with 98 additions and 125 deletions
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12
src/backend/optimizer/path/costsize.c
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@@ -42,7 +42,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.86 2002/06/25 17:27:20 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.87 2002/06/25 17:58:10 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@@ -154,11 +154,11 @@ cost_seqscan(Path *path, Query *root,
*
* Given a guesstimated cache size, we estimate the actual I/O cost per page
* with the entirely ad-hoc equations:
* if relpages >= effective_cache_size:
* random_page_cost * (1 - (effective_cache_size/relpages)/2)
* if relpages < effective_cache_size:
* 1 + (random_page_cost/2-1) * (relpages/effective_cache_size) ** 2
* These give the right asymptotic behavior (=> 1.0 as relpages becomes
* for rel_size <= effective_cache_size:
* 1 + (random_page_cost/2-1) * (rel_size/effective_cache_size) ** 2
* for rel_size >= effective_cache_size:
* random_page_cost * (1 - (effective_cache_size/rel_size)/2)
* These give the right asymptotic behavior (=> 1.0 as rel_size becomes
* small, => random_page_cost as it becomes large) and meet in the middle
* with the estimate that the cache is about 50% effective for a relation
* of the same size as effective_cache_size. (XXX this is probably all