Re: pg_sleep_enhancements.patch

2014-01-29 Vik Fearing <vik(dot)fearing(at)dalibo(dot)com>

> On 01/29/2014 08:04 PM, Pavel Stehule wrote:
> > Hello
> >
> > I am looking on this patch
>
> Thank you for looking at it.
>
> > http://www.postgresql.org/message-id/525FE206.6000502@dalibo.com
> >
> > a) pg_sleep_for - no objection - it is simple and secure
>
> Okay.
>
> > b) pg_sleep_until
> >
> > I am not sure - maybe this implementation is too simply. I see two
> > possible risk where it should not work as users can expect
> >
> > a) what will be expected behave whem time is changed - CET/CEST ?
>
> There is no risk there, the wake up time is specified with time zone.
>
> > b) what will be expected behave when board clock is not accurate and
> > it is periodically fixed (by NTP) - isn't better to sleep only few
> > seconds and recalculate sleeping interval?
>
> We could do that, but it seems like overkill. It would mean writing a
> new C function whereas this is just a simple helper for the existing
> pg_sleep() function. So my vote is to keep the patch as-is.
>
>
Ok

second question - is not this functionality too dangerous? If somebody use
it as scheduler, then

a) can holds connect, session data, locks too long time
b) it can stop on query timeout probably much more early then user expect

What is expected use case?

Regards

Pavel

> --
> Vik
>
>