From: | Dan Harris <fbsd(at)drivefaster(dot)net> |
---|---|
To: | pgsql-admin(at)postgresql(dot)org |
Subject: | Re: finding fragmented tables |
Date: | 2007-05-10 04:15:51 |
Message-ID: | 46429C77.5090302@drivefaster.net |
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Thread: | |
Lists: | pgsql-admin |
Carin Westblom wrote:
> How can I easily find specific tables and/or databases with a lot of
> space that may be reclaimed w a vacuum full?
>
I picked up this tip on the list a while ago:
SELECT pg_namespace.nspname, pg_class.relname, pg_class.reltuples,
pg_class.relpages, rowwidths.avgwidth, ceil(pg_class.reltuples *
rowwidths.avgwidth::double precision /
current_setting('block_size'::text)::double precision) AS expectedpages,
pg_class.relpages::double precision / ceil(pg_class.reltuples *
rowwidths.avgwidth::double precision /
current_setting('block_size'::text)::double precision) AS bloat,
ceil((pg_class.relpages::double precision *
current_setting('block_size'::text)::double precision - ceil(pg_class.reltuples
* rowwidths.avgwidth::double precision)) / 1024::double precision) AS wastedspace
FROM ( SELECT pg_statistic.starelid, sum(pg_statistic.stawidth) AS avgwidth
FROM pg_statistic
GROUP BY pg_statistic.starelid) rowwidths
JOIN pg_class ON rowwidths.starelid = pg_class.oid
JOIN pg_namespace ON pg_namespace.oid = pg_class.relnamespace
WHERE pg_class.relpages > 1;
then do:
select * from relbloat order by wastedspace desc;
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