Re: specific query (not all) on Pg8 MUCH slower than Pg7
От | Bill Moran |
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Тема | Re: specific query (not all) on Pg8 MUCH slower than Pg7 |
Дата | |
Msg-id | 20070508110427.c714d52f.wmoran@collaborativefusion.com обсуждение исходный текст |
Ответ на | Re: specific query (not all) on Pg8 MUCH slower than Pg7 ("Alexander Staubo" <alex@purefiction.net>) |
Список | pgsql-performance |
In response to "Alexander Staubo" <alex@purefiction.net>: > On 5/8/07, Tom Lane <tgl@sss.pgh.pa.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@collaborativefusion.com Phone: 412-422-3463x4023
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