From: Qingqing Zhou <zhouqq@cs.toronto.edu>
To: pgsql-performance@postgresql.org
Subject: Re: Help in avoiding a query 'Warm-Up' period/shared buffer cache
Date: Thu, 5 Jan 2006 22:08:05 -0500
Message-ID: <dpkms7$1van$1@news.hub.org> (raw)
References: <200601041449.43557.mliberman@mixedsignals.com>
<dpk922$slo$1@news.hub.org>
<200601051815.36181.mliberman@mixedsignals.com>
"Mark Liberman" <mliberman@mixedsignals.com> wrote
>
> Now, my follow-up question / assumption. I am assuming that the IO time
> is
> so long on that index because it has to read the entire index (for that
> file_id) into memory
>
> any confirmation / corrections to my assumptions are greatly appreciated.
> E.g. is
> the compound index the way to go, or the solo index on file_id?
>
Only part of the index file is read. It is a btree index. Keep the index
smaller but sufficient to guide your search is always good because even by
the guidiance of the index, a heap visit to get the real data is not
avoidable.
Regards,
Qingqing
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To: pgsql-performance@postgresql.org
Cc: zhouqq@cs.toronto.edu
Subject: Re: Help in avoiding a query 'Warm-Up' period/shared buffer cache
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