Re: hot_standby_feedback

On Thu, Aug 29, 2013 at 2:44 PM, Tatsuo Ishii <ishii@postgresql.org> wrote:
> I have a question about hot_standby_feedback parameter. In my
> understanding, if this parameter is on, a long running transaction on
> standby will not be canceled even if the transaction conflicts.

> As you can see vacuum on the primary removes all the rows in t1. I
> thought vacuum will not make the page entriely empty because
> of the effect of hot_standby_feedback.
>
> After while, on standby:
> test=# select * from t1;
> FATAL:  terminating connection due to conflict with recovery
> DETAIL:  User was holding a relation lock for too long.
> HINT:  In a moment you should be able to reconnect to the database and repeat your command.
>
> Again, this is not what I expected. Am I missing something?

I also expected this behavior, and suffer similar problems with
PostgreSQL 9.1. I reported this as BUG #7546 with a test case and
raised it a few times on the mailing lists, but am no closer to a
solution.