Re: How should the waiting backends behave in sync rep? - Mailing list pgsql-hackers

From Robert Haas
Subject Re: How should the waiting backends behave in sync rep?
Date
Msg-id AANLkTimDUiRrrWzZ2ZXWSRfeP5tHm9PGmpp6zfqaFpte@mail.gmail.com
Whole thread Raw
In response to How should the waiting backends behave in sync rep?  (Fujii Masao <masao.fujii@gmail.com>)
Responses Re: How should the waiting backends behave in sync rep?
List pgsql-hackers
On Tue, Mar 8, 2011 at 10:06 AM, Fujii Masao <masao.fujii@gmail.com> wrote:
> How should the backends waiting for replication behave when
> synchrnous_standby_names
> is set to '' and the configuration file is reloaded? Now they keep
> waiting for the ACK from the
> standby. But I think that it's more natural for them to get out of the
> wait state and complete
> the transaction in that case. If we'll change them in that way, we
> would no longer need
> something like "pg_ctl standalone" which I mentioned in another thread. Thought?

I think so.  Looking at assign_synchronous_standby_names, the
following code just looks wrong:
       if (doit && list_length(elemlist) > 0)               sync_standbys_defined = true;

Once sync_standbys_defined becomes true, there's no way for it to ever
become false again.  That can't be right.  That means that if you
disable sync rep by zeroing out synchronous_standby_names, backends
that already existed at the time you made the change will continue to
act as though sync rep is enabled until they exit.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


pgsql-hackers by date:

Previous
From: Robert Haas
Date:
Subject: Re: Update of replication/README
Next
From: "Kevin Grittner"
Date:
Subject: Re: wrap alpha4 tomorrow ~9am Eastern (was: Alpha4 release blockers)