Re: Index Bloat - how to tell?

On 15/12/10 09:12, Dave Crooke wrote:
> There is a plugin called pgstattuple which can be quite informative
> .... however, it actually does a full scan of the table / index files,
> which may be a bit invasive depending on your environment and load.
>
> http://www.postgresql.org/docs/current/static/pgstattuple.html
>
> It's in the contrib (at least for 8.4), and so you have to import its
> functions into your schema using the script in the contrib directory.
>

If you are using 8.4 or later, try the Freespacemap module:

http://www.postgresql.org/docs/current/static/pgfreespacemap.html

I tend to run this query:

SELECT oid::regclass,
pg_relation_size(oid)/(1024*1024) AS mb,
sum(free)/(1024*1024) AS free_mb
FROM
(SELECT oid, (pg_freespace(oid)).avail AS free
FROM pg_class) AS a
GROUP BY a.oid ORDER BY free_mb DESC;

to show up potentially troublesome amounts of bloat.

regards

Mark