Re: Memory contexts reset for trigger invocations

Hi,

On February 5, 2019 7:55:28 PM GMT+05:30, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>Andres Freund <andres(at)anarazel(dot)de> writes:
>> Wouldn't it be better to reset an appropriate context after each
>> invocation? Yes, that'd require some care to manage the lifetime of
>> tuples returned by triggers, but that seems OK?
>
>I'm not sure that we can change much here without effectively breaking
>the trigger-function API.

HM, why? If we copy the tuple into a longer lived context we ought to be able to reset more aggressively.

I doubt that there's enough win to be had
>to justify forcing external PLs etc to change.
>
>Having said that, I recall that that API was kind of a pain in the
>rear when I was redoing plpgsql's handling of composite variables
>last year. Don't recall details right now (ENOCAFFEINE). Maybe
>a wholesale rethink would be justified? But I'm not excited about
>just twiddling things at the margin.

Yea, we probably ought to: The pluggable storage patch set makes trigger.c use slots. But the trigger interface requires heap tuples, so we extract heap tuples. But probably it'd be go full in slots at some point.

Regards,

Andres
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