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The attached patch fixes some spelling mistakes, makes the

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comments on one of the optimizer functions a lot more
clear, adds a summary of the recent KSQO discussion to the
comments in the code, adds regression tests for the bug with
sequence state Tom fixed recently and another reg. test, and
removes some PostQuel legacy stuff: ExecAppend -> ExecInsert,
ExecRetrieve -> ExecSelect, etc. This was changed because the
elog() messages from this routine are user-visible, so we
should be using the SQL terms.

Neil Conway
This commit is contained in:
Bruce Momjian
2002-06-25 17:27:20 +00:00
parent 8a9462867a
commit ed275aea42
13 changed files with 125 additions and 98 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 1.85 2002/06/20 20:29:29 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.86 2002/06/25 17:27:20 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:
* 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
* 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
* 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