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Re-add item with better description:

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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