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References: <4D53CA4F020000250003A789@gw.wicourts.gov>
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Date: Sun, 5 Jun 2011 16:25:39 +0100
Message-ID: <BANLkTimE3isrTRmZFG8obsvYJCUxSmJzaA@mail.gmail.com>
Subject: Re: Why we don't want hints Was: Slow count(*) again...
From: =?ISO-8859-2?Q?pasman_pasma=F1ski?= <pasman.p@gmail.com>
To: "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
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Hi. I have the idea: hints joined to function. For example instead of

WHERE table1.field1=3Dtable2.field2
write:
WHERE specificeq(table1.field1,table2.field2)

and hints add to declaration of specificeq function.

2011/2/23, Robert Haas <robertmhaas@gmail.com>:
> On Wed, Feb 16, 2011 at 4:22 PM, Bruce Momjian <bruce@momjian.us> wrote:
>> I am not excited about the idea of putting these correlations in
>> queries. =A0What would be more intesting would be for analyze to build a
>> correlation coeffficent matrix showing how columns are correlated:
>>
>> =A0 =A0 =A0 =A0a =A0 b =A0 c
>> =A0 =A0a =A0 1 =A0 .4 =A00
>> =A0 =A0b =A0 .1 =A01 =A0 -.3
>> =A0 =A0c =A0 .2 =A0.3 =A01
>>
>> and those correlations could be used to weigh how the single-column
>> statistics should be combined.
>
> If you can make it work, I'll take it... it's (much) easier said than
> done, though.
>
> --
> Robert Haas
> EnterpriseDB: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
>
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pasman