| 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 |
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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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