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Re: Precomputed constants?

From: "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
To: Zoltan Boszormenyi <zboszor(at)dunaweb(dot)hu>
Cc: Volkan YAZICI <yazicivo(at)ttnet(dot)net(dot)tr>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Precomputed constants?
Date: 2006-06-15 15:59:29
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
On Thu, Jun 15, 2006 at 06:31:02AM +0200, Zoltan Boszormenyi wrote:
> Jim C. Nasby ?rta:
> >On Wed, Jun 14, 2006 at 01:30:10PM +0200, B?sz?rm?nyi Zolt?n wrote:
> >  
> >>Replacing random() with a true constant gives me index scan
> >>even if it's hidden inside other function calls. E.g.:
> >>    
> >
> >The database has no choice but to compute random() for every row; it's
> >marked VOLATILE.
> >  
> I see now, docs about CREATE FUNCTION mentions random(),
> currval() and timeofday() as examples for VOLATILE.
> But where in the documentation can I find this info about all
> built-in functions? Thanks.

No, but you can query pg_proc for that info. The docs should have info
about that table.
Jim C. Nasby, Sr. Engineering Consultant      jnasby(at)pervasive(dot)com
Pervasive Software    work: 512-231-6117
vcard:       cell: 512-569-9461

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