From: Michael Fuhr <mike@fuhr.org>
To: Scott Marlowe <scott.marlowe@gmail.com>
Cc: salman <salmanb@quietcaresystems.com>
Cc: pgsql-novice@postgresql.org
Cc: pgsql-admin@postgresql.org
Cc: pgsql-performance@postgresql.org
Subject: Re: [PERFORM] Question about CLUSTER
Date: Mon, 11 Feb 2008 19:42:19 -0700
Message-ID: <20080212024219.GA42737@winnie.fuhr.org> (raw)
In-Reply-To: <dcc563d10802111333o535bfc8xd28efd7d2c5e0d26@mail.gmail.com>
References: <47B0AA1F.8040101@quietcaresystems.com>
<dcc563d10802111333o535bfc8xd28efd7d2c5e0d26@mail.gmail.com>
On Mon, Feb 11, 2008 at 03:33:37PM -0600, Scott Marlowe wrote:
> On Feb 11, 2008 2:03 PM, salman <salmanb@quietcaresystems.com> wrote:
> > I'm planning to cluster a few large tables in our database but I'm
> > unable to find any recommendations/documentation on best practices --
> > Mainly, whether it's better to use an index which has a higher idx_scan
> > value, a higher idx_tup_read value, or the higest idx_tup_fetch value.
> >
> > I'm assuming that idx_tup_read would probably be the best choice, but
> > want to get other opinions before proceeding.
>
> If you've got two indexes that are both being hit a lot, it might be
> worth looking into their correlation, and if they get used a lot
> together, look at creating an index on both.
>
> But I'd guess that idx_tup_read would be a good bet.
You might also consider the ratio idx_tup_read::float8 / idx_scan
to see which indexes access a lot of rows per scan.
--
Michael Fuhr
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To: pgsql-performance@postgresql.org
Cc: mike@fuhr.org, scott.marlowe@gmail.com, salmanb@quietcaresystems.com, pgsql-novice@postgresql.org, pgsql-admin@postgresql.org
Subject: Re: [PERFORM] Question about CLUSTER
In-Reply-To: <20080212024219.GA42737@winnie.fuhr.org>
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