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< * 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
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<   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.
This commit is contained in:
Bruce Momjian
2005-04-25 15:35:32 +00:00
parent 61cf53516e
commit 238fb0342e
2 changed files with 8 additions and 6 deletions
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7
doc/TODO
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@ -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