Re: regression, deadlock in high frequency single-row UPDATE

On 09/12/14 12:55, Andrew Sackville-West wrote:
> Some months later (stupid business priorities...) we have something to
> report on this. We have been able to produce a minimal schema to
> demonstrate the problem, and successfully induced the deadlock using
> pgbench (thanks to Paulo Tanimoto, cc-ed here).
>
> Please see:
>
> https://gist.github.com/andrewsw-janrain/40d1687db013b1e7c3b3
>
> for detailed instructions on how to trigger the deadlock.
>
> I would be thrilled to learn that we've done something wrong here,
> otherwise I think this represents a regression introduced in 9.3.
>
>


That is interesting - FWIW I can reproduce:

- 9.2.9 no deadlock
- 9.4rc1 many deadlocks

so something has changed after 9.2 for sure!

Just mucking about I changed certain things in your schema setup
(removed ON DELETE CASCADE, use CURRENT_TIMESTAMP instead of
now()...lessen the use of DEFAULT)...however still seeing deadlocks in
9.4, so at least it is easy to reproduce!

Regards

Mark