Re: TRUNCATE pg_largeobject

Hi Dmitriy,

pg_largeobject is already empty, I have lo_unlink()'ed everything
from it, but it still takes up the same disk space and memory for
the free page maps. I'm looking at the best way to reclaim the
disk/memory from this otherwise empty table.
Normal VACUUM didn't help and I'd like some advice whether to use
VACUUM FULL or TRUNCATE.

-Tamas


> Hey Tamas,
>
> 2011/7/25 Tamas Vincze <vincze@neb.com <mailto:vincze@neb.com>>
>
>     Is it safe?
>
>     This table is around 500GB and because of performance reasons
>     I slowly moved all large objects to regular files on a NetApp
>     share.
>
>     Now it shows 0 records:
>
>     # select count(*) from pg_largeobject;
>      count
>     -------
>         0
>     (1 row)
>
>     but disk space and RAM by the free space map is still occupied.
>     I'd like to clean it up.
>     A VACUUM FULL would probably do it, but it would take several
>     hours with heavy I/O and I'd like to avoid that on a production
>     server.
>
>     Can I safely issue a "TRUNCATE pg_largeobject"?
>     It is v8.1.9.
>
>     Thanks!
>
> I think that SELECT lo_unlink(loid) FROM (SELECT DISTINCT loid FROM
> pg_largeobject) AS foo
> would be better than direct truncation.
>
>
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>
> --
> // Dmitriy.
>
>