On 21.03.2013 05:36, Tom Lane wrote:
> Simon Riggs<simon@2ndQuadrant.com> writes:
>> On 20 March 2013 18:02, Tom Lane<tgl@sss.pgh.pa.us> wrote:
>>> The API that comes to mind is (name subject to
>>> bikeshedding)
>>>
>>> pg_blocking_pids(pid int) returns int[]
>
>> Useful. Can we also have an SRF rather than an array?
>
> I thought about that, but at least for the isolationtester use-case,
> the array result is clearly easier to use. You can get from one to the
> other with unnest() or array_agg(), so I don't really feel a need to
> provide both. Can you generate use-cases where the set-result approach
> is superior?
How about inverting the function into:
pg_pid_blocked_by(pid int) returns int
It would take as argument a pid, and return the pid of the process that
is blocking the given process. That would feel more natural to me.
- Heikki
