Re: Calculated view fields (8.1 != 8.2)

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Tom Lane wrote:
> Gaetano Mendola <gmendola(at)mbigroup(dot)it> writes:
>> I can immagine a case when a lower module exports a view to upper layer stating
>> the interface as list of fields:
>
>> first_name, last_name, ....
>
>> with an *hidden* field that is a function call that updates the statistics on
>> how many time a given record was selected, then this technique can not be used
>> anymore starting with 8.2.x.
>
> You're living in a dream world if you think that works reliably in *any*
> version of Postgres. But for starters, what is your definition of
> "selected" --- pulled from the physical table? Accumulated into an
> aggregate? Delivered as a recognizable row to the client? Delivered N
> times to the client due to joining N times to some other table?

Well that was a not good example, I don't have any problem in mark from now
on all my function as stable/immutable (the one I use on views) but still
I believe is source of bad performance evaluate a function on rows discarded and
at same time this break the principle of least surprise.

Regards
Gaetano Mendola

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