From: Pavan Deolasee <pavan.deolasee@gmail.com>
To: Gauri Kanekar <meetgaurikanekar@gmail.com>
Cc: Andrew Sullivan <ajs@commandprompt.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Replication Syatem
Date: Tue, 29 Apr 2008 11:25:27 +0530
Message-ID: <2e78013d0804282255t48285141pf49d71bb63e8cf48@mail.gmail.com> (raw)
In-Reply-To: <7e4ba9550804282246p73c62fc6y5e7cb7dda55a6b50@mail.gmail.com>
References: <7e4ba9550804280638ie81dc23w472785c83cd38fcf@mail.gmail.com>
<a2de01dd0804280658t68ac22dsf182d304a94de5a2@mail.gmail.com>
<7e4ba9550804280705q43c51e66l104a5ff9272bbd4d@mail.gmail.com>
<20080428162243.GN2970@commandprompt.com>
<7e4ba9550804282246p73c62fc6y5e7cb7dda55a6b50@mail.gmail.com>
On Tue, Apr 29, 2008 at 11:16 AM, Gauri Kanekar
<meetgaurikanekar@gmail.com> wrote:
> Andrew,
>
> Can you explain me in detail why u said vacuum full is making the things
> worst.
1. VACUUM FULL takes exclusive lock on the table. That makes table
unavailable for read/writes.
2. VACUUM FULL moves live tuples around. When a tuple is moved, the
old index entry is deleted and a new index entry is inserted. This
causes index bloats which are hard to recover.
> We do vacuum full, as vacuum verbose analyse dont regain space for us.
>
As I mentioned in the other reply, you are not gaining much by
regaining space. The subsequent UPDATEs/INSERTs will quickly extend
the relation and you loose all the work done by VACUUM FULL. Plain
VACUUM will update FSM to track the free space scattered across the
relation which is later reused by updates/inserts.
Thanks,
Pavan
--
Pavan Deolasee
EnterpriseDB http://www.enterprisedb.com
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: pavan.deolasee@gmail.com, meetgaurikanekar@gmail.com, ajs@commandprompt.com
Subject: Re: Replication Syatem
In-Reply-To: <2e78013d0804282255t48285141pf49d71bb63e8cf48@mail.gmail.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox