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

Andrew Sackville-West <awest@janrain.com>

From: Andrew Sackville-West <awest@janrain.com>
To: Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>, pgsql-bugs@postgresql.org, Paulo Tanimoto <paulo@janrain.com>
Date: 2014-12-09T17:28:52Z
Lists: pgsql-bugs
On Mon, Dec 8, 2014 at 9:58 PM, Mark Kirkwood <mark.kirkwood@catalyst.net.nz
> wrote:

> On 09/12/14 12:55, Andrew Sackville-West wrote:
>
>>
>> https://gist.github.com/andrewsw-janrain/40d1687db013b1e7c3b3
>>
>> for detailed instructions on how to trigger the deadlock.
>
>

>
>>
> 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!
>

Can you speak to what benefits those changes might yield? Or point to
relevant docs?

thanks

A


>
> Regards
>
> Mark
>
>
>
>
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Commits

  1. Add isolationtester spec for old heapam.c bug

  2. Improve concurrency of foreign key locking