Re: Stable functions problem

From: Gaetano Mendola <mendola(at)bigfoot(dot)com>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Stable functions problem
Date: 2004-12-20 10:45:52
Message-ID: cq6agu$nal$1@floppy.pyrenet.fr
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Tom Lane wrote:
> Gaetano Mendola <mendola(at)bigfoot(dot)com> writes:
>
>>I'm having a bounce of errors because IMMUTABLE and STABLE
>>attributes for some of my functions. Let me explain with an example,
>
>
> Hmm. This particular example is a bug in exec_eval_simple_expr() ...
> if we're going to bypass SPI then we'd better do the things SPI does
> that are needed to maintain the correct execution environment, and
> as of 8.0 one of those things is to advance ActiveSnapshot.
> I've applied a patch for this.

Thank you. I'll try with the CVS version and I'll let you know.

> (Memo to self: I'm beginning to wonder
> if exec_eval_simple_expr is worth the trouble at all, compared to just
> using SPI. The amount of overhead it saves seems to get less with each
> new release.)
>
>
>>now here I can continue my function using the my_id_user, unfortunatelly
>>that sp_id_user is declared as IMMUTABLE this mean that at the second call
>>of sp_id_user my_id_user will not contain the user id.
>
>
> That actually doesn't have anything to do with it --- the same failure
> would have occurred if you'd (correctly) declared sp_id_user as STABLE.
> So it's a good bug report.

Indeed I had the same "problem" declaring it as STABLE.

> But I trust you do realize you are playing with fire. While I have been
> heard to suggest mislabeling functions as immutable if they're only
going
> to be used in interactive queries,
> I don't think I have ever failed to mention that you *will* get burnt
> if you call such functions from other functions. When this coding
> someday does break for you, I won't have any sympathy at all...

Yes, I'll take your suggestion as gold.

Regards
Gaetano Mendola

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