Message-ID: <487FD8A3.6080405@une.edu.au>
Date: Fri, 18 Jul 2008 09:41:23 +1000
From: Klint Gore <kgore4@une.edu.au>
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To: Kevin Duffy <KD@wrinvestments.com>
CC: pgsql-general@postgresql.org
Subject: Re: query optimization
References: <DFC309C8A42633419600522FA8C4AE1A560DB4@mail-01.wrcapital.corp>
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Kevin Duffy wrote:
>
> So here are the questions for the PSQL gurus:
>
> Is getsectypekey(‘CFD’) executing for every join (or possible join) 
> between positions_gsco and security?
>
> Causing a scan of security for every possible join.
>
> Does ‘ (select getsectypekey('CFD') ) ‘ cause the getsectype() 
> function to be executed once and thus
>
> allowing the index on security to be used.
>
> And of couse ‘5’ makes things simple. The index on security is used.
>
> Am I posting this in the right. If not please help me correct my error 
> and point me to the correct spot.
>

Is the function stable or volatile?

As Scott Marlowe suggested, you need to look at the explain results to 
find out what the plan is in each case.

klint.

-- 
Klint Gore
Database Manager
Sheep CRC
A.G.B.U.
University of New England
Armidale NSW 2350

Ph: 02 6773 3789  
Fax: 02 6773 3266
EMail: kgore4@une.edu.au