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From: Gregory Stark <stark@enterprisedb.com>
To: Pavan Deolasee <pavan.deolasee@gmail.com>
Cc: Gauri Kanekar <meetgaurikanekar@gmail.com>
Cc: Greg Smith <gsmith@gregsmith.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Replication Syatem
Date: Tue, 29 Apr 2008 09:48:31 -0400
Message-ID: <87lk2w4vrk.fsf@oxford.xeocode.com> (raw)
In-Reply-To: <2e78013d0804290425n402f5e94i90bc7206aeefffdc@mail.gmail.com>
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"Pavan Deolasee" <pavan.deolasee@gmail.com> writes:

>> Any special guideline to follow to make HOT working??
>>
>
> You can do couple of things to benefit from HOT.
>
> 1. HOT addresses a special, but common case where UPDATE operation
> does not change any of the index keys. So check if your UPDATE changes
> any of the index keys. If so, see if you can avoid having index
> involving that column. Of course, I won't advocate dropping an index
> if it would drastically impact your frequently run queries.
>
> 2. You may leave some free space in the heap (fillfactor less than
> 100). My recommendation would be to leave space worth of one row or
> slightly more than that to let first UPDATE be an HOT update.
> Subsequent UPDATEs in the page may reuse the dead row created by
> earlier UPDATEs.
>
> 3. Avoid any long running transactions.

Perhaps we should put this list in the FAQ.

-- 
  Gregory Stark
  EnterpriseDB          http://www.enterprisedb.com
  Ask me about EnterpriseDB's 24x7 Postgres support!



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