Re: TRUNCATE pg_largeobject - Mailing list pgsql-general

From Dmitriy Igrishin
Subject Re: TRUNCATE pg_largeobject
Date
Msg-id CAAfz9KNtL=JKjQ_zThk52iQT5NTwQtC6NpGydZYOS2u-2N+UMw@mail.gmail.com
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In response to TRUNCATE pg_largeobject  (Tamas Vincze <vincze@neb.com>)
Responses Re: TRUNCATE pg_largeobject
List pgsql-general
Hey Tamas,

2011/7/25 Tamas Vincze <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.


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