Re: Large DB, several tuning questions: Index sizes, VACUUM, REINDEX, Autovacuum

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От Andres Freund
Тема Re: Large DB, several tuning questions: Index sizes, VACUUM, REINDEX, Autovacuum
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Msg-id 200912061751.20080.andres@anarazel.de
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Ответ на Large DB, several tuning questions: Index sizes, VACUUM, REINDEX, Autovacuum  (Andreas Thiel <andreas.thiel@u-blox.com>)
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Hi Andreas,

Could you please properly quote the email? The way you did it is quite
unreadable because you always have to guess who wrote what.

On Sunday 06 December 2009 17:06:39 Andreas Thiel wrote:
> > I'm going to work on the table size of the largest table (result_orig)
> > itself by eliminating columns, stuffing n Booleans into bit(n)'s,
> > replacing double precision by reals, etc.. By this I should be able to
> > reduce the storage per row to ~1/3 of the bytes currently used.
> That sounds rather ambitous - did you factor in the per row overhead?
> I did now create the new table, I have now 63 instead of 94 bytes/row on
> average. So yes you're right I'm about to hit the bottom of the per row
> overhead.
How did you calculate that? Did you factor in the alignment requirements? The
ddl would be helpfull...

> Btw, have you possibly left over some old prepared transactions or an
> idle in
> transaction connection? Both can lead to sever bloat.
> For the former you can check the system table pg_prepared_xact for the
> latter
> pg_stat_activity.
> Seems no the case, pg_prepared_xact doesn't even exist.
Its pg_prepared_xacts (note the s), sorry my mind played me.

> Where would I find that postmaster output? In syslog? There's nothing
> visible...
Depends on your setup. I have not the slightest clue about centos. If
necessary start postmaster directly.

> > max_fsm_relations = 4194304             # min 100, ~70 bytes each
Have you corrected that value?


Andres

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