From: | Gaetano Mendola <mendola(at)bigfoot(dot)com> |
---|---|
To: | pgsql-hackers(at)postgreSQL(dot)org |
Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Subject: | Re: Calculated view fields (8.1 != 8.2) |
Date: | 2007-03-08 18:35:31 |
Message-ID: | 45F05773.6000607@bigfoot.com |
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Lists: | pgsql-hackers |
Tom Lane wrote:
> Gaetano Mendola <mendola(at)bigfoot(dot)com> writes:
>> [ 8.2 evaluates volatile functions in the targetlist of a view ]
>> If I mark the function as STABLE or IMMUTABLE then even with version
>> 8.2 the function is not evaluated. Is this the intended behavior?
>
> Yes; people complained that we needed to be more careful about the
> number of times volatile functions get evaluated.
I suspect that functions are evaluated also for record discarded due to
joins. Is that the case?
Like:
SELECT * FROM ta JOIN tb USING (id) where tb.foo = 4;
If ta is a view with some calculated fields are the function on ta
evaluated only for record matching the filters or in some case (
like a full scan on ta ) also for the records discarded due to the join?
Regards
Gaetano Mendola
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