Re: Server-side hooks for user session start and session end

2015-09-26 19:59 GMT+02:00 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:

> Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> writes:
> > 2015-09-26 19:53 GMT+02:00 Nikolai Zhubr <n-a-zhubr(at)yandex(dot)ru>:
> >> And the events of session start and session end would seem quite generic
> >> and usefull anyway?
>
> > I don't know. I am pretty sceptical - from my experience this request was
> > related to unhappy designed projects.
>
> A session-end hook seems pretty problematic to me: you simply cannot
> guarantee that it will run at all. (Consider process crash or server
> abort cases.) So anything built on the assumption that it gets to run
> at session end is going to be inherently unreliable.
>
> A session-start hook is already possible at the C-code level, using
> session_preload_libraries. It wouldn't be hard to write an extension
> that exposed that in some useful way to SQL code.
>

years ago I tried it, if I remember well. I had a problems with SPI calls,
because some caches was not initialized. I am not sure, and I didn't test
last time.

Regards

Pavel

>
> regards, tom lane
>