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> * Allow ORDER BY ... LIMIT 1 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 1 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.
>
This commit is contained in:
Bruce Momjian 2005-04-25 13:03:37 +00:00
parent c5b08d3b7d
commit 61cf53516e
2 changed files with 15 additions and 2 deletions
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9
doc/TODO
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@ -2,7 +2,7 @@
PostgreSQL TODO List
====================
Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
Last updated: Sun Apr 24 21:42:27 EDT 2005
Last updated: Mon Apr 25 09:03:30 EDT 2005
The most recent version of this document can be viewed at
http://www.postgresql.org/docs/faqs.TODO.html.
@ -862,6 +862,13 @@ Optimizer / Executor
====================
* Add missing optimizer selectivities for date, r-tree, etc
* Allow ORDER BY ... LIMIT 1 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 1 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.
* Precompile SQL functions to avoid overhead
* Create utility to compute accurate random_page_cost value
* Improve ability to display optimizer analysis using OPTIMIZER_DEBUG

8
doc/src/FAQ/TODO.html
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@ -8,7 +8,7 @@
<body bgcolor="#FFFFFF" text="#000000" link="#FF0000" vlink="#A00000" alink="#0000FF">
<h1><a name="section_1">PostgreSQL TODO List</a></h1>
<p>Current maintainer: Bruce Momjian (<a href="mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</a>)<br/>
Last updated: Sun Apr 24 21:42:27 EDT 2005
Last updated: Mon Apr 25 09:03:30 EDT 2005
</p>
<p>The most recent version of this document can be viewed at<br/>
<a href="http://www.postgresql.org/docs/faqs.TODO.html">http://www.postgresql.org/docs/faqs.TODO.html</a>.
@ -787,6 +787,12 @@ first.
<ul>
<li>Add missing optimizer selectivities for date, r-tree, etc
</li><li>Allow ORDER BY ... LIMIT 1 to select high/low value without sort or
index using a sequential scan for highest/lowest values
<p> Right now, if no index exists, ORDER BY ... LIMIT 1 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.
</p>
</li><li>Precompile SQL functions to avoid overhead
</li><li>Create utility to compute accurate random_page_cost value
</li><li>Improve ability to display optimizer analysis using OPTIMIZER_DEBUG