Re: Sync Rep v19

On Sun, 2011-03-06 at 16:58 +0900, Fujii Masao wrote:
> On Sun, Mar 6, 2011 at 4:51 PM, Fujii Masao <masao.fujii@gmail.com> wrote:
> > One comment; what about introducing built-in function to wake up all the
> > waiting backends? When replication connection is closed, if we STONITH
> > the standby, we can safely (for not physical data loss but logical one)
> > switch the primary to standalone mode. But there is no way to wake up
> > the waiting backends for now. Setting synchronous_replication to OFF
> > and reloading the configuration file doesn't affect the existing waiting
> > backends. The attached patch introduces the "pg_wakeup_all_waiters"
> > (better name?) function which wakes up all the backends on the queue.
> 
> If unfortunately all connection slots are used by backends waiting for
> replication, we cannot execute such a function. So it makes more sense
> to introduce something like "pg_ctl standalone" command?

Well, there is one way to end the wait: shutdown, or use
pg_terminate_backend().

If you simply end the wait you will get COMMIT messages.

What I would like to do is commit the "safe" patch now. We can then
discuss whether it is safe and desirable to relax some aspects of that
during beta.

-- Simon Riggs           http://www.2ndQuadrant.com/books/PostgreSQL Development, 24x7 Support, Training and Services