Re: 'tuple concurrently updated' error when granting permissions

On 02/27/2014 06:54 PM, Jason Daly wrote:
> Hi,
> When I attempt to execute the non-query "GRANT SELECT ON TABLE
> <schema>.<table> TO <role>", I occasionally encounter an exception from
> postgresql, 'tuple concurrently updated'.
>
> I think the tuple it is referring to is the role.
>
> Our app is multi-threaded, and it is very possible for more than one
> thread to be attempting to grant permissions to the same role at the
> same time. (the situation is that we are creating tables on the fly, and
> each time we create a new table we have to grant permissions to a role
> so it can read from it).
>
> In my view, it is a bug that postgresql cannot handle multiple
> concurrent grants to a role.
>
> We're using the latest version of postgresql (9.3) in the context of an
> AWS RDS.
>
> Should I enter a bug report, or can someone convince me that we should
> single-thread this part of our app (or work around it somehow)?

My guess this is covered here:

http://rhaas.blogspot.com/2013/07/mvcc-catalog-access.html

In the meantime, I would say single thread is the order of the day.

>
> Please respond to jasondaly(at)trimblegeospatial(dot)com
> <mailto:jasondaly(at)trimblegeospatial(dot)com>
>
> -Jason
>

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com