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Re: performance issue: logical operators are slow inside SQL function: missing optimalization?

From: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Martijn van Oosterhout <kleptog(at)svana(dot)org>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: performance issue: logical operators are slow inside SQL function: missing optimalization?
Date: 2010-08-29 18:15:47
Message-ID: AANLkTi=n_aiOAVU+z+OUngzwdcb2mCMX25Sg+Zdt0nYQ@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
2010/8/29 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
> Martijn van Oosterhout <kleptog(at)svana(dot)org> writes:
>> On Sun, Aug 29, 2010 at 11:23:29AM -0400, Tom Lane wrote:
>>> It has nothing to do with boolean operators, just double evaluation.
>
>> I was wondering, wouldn't it be possible to avoid the double evaluation
>> by simply creating an extra slot for the intermediate value.
>
> Possibly, but the trick would be to figure out when to evaluate the
> values so that it would still behave the same as without inlining.
> I don't think the existing Param mechanism could do this without
> some additional help.
>

maybe subject for ToDo?

Regards

Pavel Stehule

>                        regards, tom lane
>

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