On 2017-01-06 10:43:32 -0500, Bruce Momjian wrote:
> On Thu, Jan  5, 2017 at 06:48:17PM -1000, Joel Jacobson wrote:
> > On Thu, Jan 5, 2017 at 4:59 PM, Bruce Momjian <br...@momjian.us> wrote:
> > > Agreed.  No need in adding overhead for short-lived locks because the
> > > milli-second values are going to be meaningless to users. I would be
> > > happy if we could find some weasel value for non-heavyweight locks.
> > 
> > To avoid a NULL value for waiting_start, and thanks to non-heavyweight
> > locks don't exceed order-of-milliseconds, I think it would be
> > acceptable to just return now() whenever something wants to know
> > waiting_start i.e. when something selects from pg_stat_activity.
> > 
> > The exact value would only be within orders-of-milliseconds away from
> > now() anyway, so one can argue it's not that important, as long as the
> > documentation is clear on that point.
> I don't think now() is a good value as it doesn't indicate to the user
> which values are real measurements and which are not.  NULL is probably
> the best.  +/-infinity is odd too.

Yea. If one wants to make NULL into now() it's trivial enough with a
single coalesce().


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