Re: Re: [COMMITTERS] pgsql: Add some isolation tests for deadlock detection and resolution.

On Fri, Feb 12, 2016 at 6:22 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> On 2016-02-12 13:16:54 -0500, Tom Lane wrote:
>> Investigation showed that there are a couple of reasons. One,
>> isolationtester's is-it-waiting query takes an insane amount of
>> time under CLOBBER_CACHE_ALWAYS --- over half a second on my
>> reasonably new server.
>
> I wonder if we shouldn't just expose a 'which pid is process X waiting
> for' API, implemented serverside. That's generally really useful, and
> looks like it's actually going to be less complicated than that
> query... And it's surely going to be faster.

If PID 12000 and PID 13000 hold AccessShareLock on relation foo, and
PID 14000 awaits AccessExclusiveLock on that relation, what does the
function return when 14000 is passed as an argument?

--
Robert Haas
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