From: | Bill Moran <wmoran(at)collaborativefusion(dot)com> |
---|---|
To: | "Alexander Staubo" <alex(at)purefiction(dot)net> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: specific query (not all) on Pg8 MUCH slower than Pg7 |
Date: | 2007-05-08 15:04:27 |
Message-ID: | 20070508110427.c714d52f.wmoran@collaborativefusion.com |
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Lists: | pgsql-performance |
In response to "Alexander Staubo" <alex(at)purefiction(dot)net>:
> On 5/8/07, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > You're not getting the indexscan optimization of the LIKE clause, which
> > is most likely due to having initdb'd the 8.1 installation in something
> > other than C locale. You can either redo the initdb in C locale (which
> > might be a good move to fix other inconsistencies from the 7.3 behavior
> > you're used to) or create a varchar_pattern_ops index on the column(s)
> > you're using LIKE with.
>
> Given the performance implications of setting the wrong locale, and
> the high probability of accidentally doing this (I run my shells with
> LANG=en_US.UTF-8, so all my databases have inherited this locale), why
> is there no support for changing the database locale after the fact?
>
> # alter database test set lc_collate = 'C';
> ERROR: parameter "lc_collate" cannot be changed
How would that command handle UTF data that could not be converted to C?
--
Bill Moran
Collaborative Fusion Inc.
http://people.collaborativefusion.com/~wmoran/
wmoran(at)collaborativefusion(dot)com
Phone: 412-422-3463x4023
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