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> * -Allow ORDER BY ... LIMIT # to select high/low value without sort or
<
<   Right now, if no index exists, ORDER BY ... LIMIT # requires we sort
<   all values to return the high/low value.  Instead The idea is to do a
<   sequential scan to find the high/low value, thus avoiding the sort.
<   MIN/MAX already does this, but not for LIMIT > 1.
<
This commit is contained in:
Bruce Momjian
2007-05-05 03:14:40 +00:00
parent d2a4a4069f
commit 71f8127bc6
2 changed files with 4 additions and 15 deletions
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doc/TODO
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@ -2,7 +2,7 @@
PostgreSQL TODO List
====================
Current maintainer: Bruce Momjian (bruce@momjian.us)
Last updated: Sun Apr 29 03:17:05 EDT 2007
Last updated: Fri May 4 23:14:29 EDT 2007
The most recent version of this document can be viewed at
http://www.postgresql.org/docs/faqs.TODO.html.
@ -1361,14 +1361,8 @@ Optimizer / Executor
====================
* Improve selectivity functions for geometric operators
* Allow ORDER BY ... LIMIT # to select high/low value without sort or
* -Allow ORDER BY ... LIMIT # to select high/low value without sort or
index using a sequential scan for highest/lowest values
Right now, if no index exists, ORDER BY ... LIMIT # requires we sort
all values to return the high/low value. Instead The idea is to do a
sequential scan to find the high/low value, thus avoiding the sort.
MIN/MAX already does this, but not for LIMIT > 1.
* Precompile SQL functions to avoid overhead
* Create utility to compute accurate random_page_cost value
* Improve ability to display optimizer analysis using OPTIMIZER_DEBUG