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| author | Bruce Momjian <bruce@momjian.us> | 2005-04-25 15:35:32 +0000 |
|---|---|---|
| committer | Bruce Momjian <bruce@momjian.us> | 2005-04-25 15:35:32 +0000 |
| commit | 238fb0342e3762764ee5a0664a1c24e81c68267b (patch) | |
| tree | 185081b75add4ad2d68bd86067d4c2ecffc2d012 | |
| parent | 61cf53516eba02f8ae58da1acfa2db6bd129cab9 (diff) | |
| download | postgresql-238fb0342e3762764ee5a0664a1c24e81c68267b.tar.gz postgresql-238fb0342e3762764ee5a0664a1c24e81c68267b.zip | |
Update description:
< * Allow ORDER BY ... LIMIT 1 to select high/low value without sort or
> * Allow ORDER BY ... LIMIT # to select high/low value without sort or
868c868
< Right now, if no index exists, ORDER BY ... LIMIT 1 requires we sort
> Right now, if no index exists, ORDER BY ... LIMIT # requires we sort
870a871
> MIN/MAX already does this, but not for LIMIT > 1.
| -rw-r--r-- | doc/TODO | 7 | ||||
| -rw-r--r-- | doc/src/FAQ/TODO.html | 7 |
2 files changed, 8 insertions, 6 deletions
@@ -2,7 +2,7 @@ PostgreSQL TODO List ==================== Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us) -Last updated: Mon Apr 25 09:03:30 EDT 2005 +Last updated: Mon Apr 25 11:35:24 EDT 2005 The most recent version of this document can be viewed at http://www.postgresql.org/docs/faqs.TODO.html. @@ -862,12 +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 +* 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 1 requires we sort + 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 diff --git a/doc/src/FAQ/TODO.html b/doc/src/FAQ/TODO.html index a4b407d153b..eba1ec7576a 100644 --- a/doc/src/FAQ/TODO.html +++ b/doc/src/FAQ/TODO.html @@ -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: Mon Apr 25 09:03:30 EDT 2005 +Last updated: Mon Apr 25 11:35:24 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>. @@ -787,11 +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 + </li><li>Allow ORDER BY ... LIMIT # 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 +<p> 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. </p> </li><li>Precompile SQL functions to avoid overhead </li><li>Create utility to compute accurate random_page_cost value |