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From: Shaun Thomas <sthomas@peak6.com>
To: Scott Marlowe <scott.marlowe@gmail.com>
Cc: Greg Smith <greg@2ndquadrant.com>
Cc: felix <crucialfelix@gmail.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: Really really slow select count(*)
Date: Fri, 4 Feb 2011 13:14:14 -0600
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On 02/04/2011 01:01 PM, Scott Marlowe wrote:

> begin;
> select * into temporaryholdingtable order by somefield;
> truncate oldtable;
> insert into oldtables select * from temporaryholdingtable;
> commit;

That's usually how I do it, except for larger tables, I also throw in a 
DROP INDEX for all the indexes on the table before the insert, and 
CREATE INDEX statements afterwards.

Which actually brings up a question I've been wondering to myself that I 
may submit to [HACKERS]: Can we add a a parallel option to the reindexdb 
command? We added one to pg_restore, so we already know it works.

I have a bunch of scripts that get all the indexes in the database and 
order them by size (so they're distributed evenly), round-robin them 
into separate REINDEX sql files, and launches them all in parallel 
depending on how many threads you want, but that's so hacky I feel dirty 
every time I use it.

-- 
Shaun Thomas
OptionsHouse | 141 W. Jackson Blvd. | Suite 800 | Chicago IL, 60604
312-676-8870
sthomas@peak6.com

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