Re: synch streaming replication question - Mailing list pgsql-general

From Michael Paquier
Subject Re: synch streaming replication question
Date
Msg-id CAB7nPqRtMj03HU+6tKQ2-XrwEA6wrP2fmQmhcKrrtWSBNZQ8gg@mail.gmail.com
Whole thread Raw
In response to synch streaming replication question  (John Wiencek <jwiencek3@comcast.net>)
Responses Re: synch streaming replication question  (Thomas Munro <thomas.munro@enterprisedb.com>)
List pgsql-general
On Tue, Feb 23, 2016 at 6:43 AM, John Wiencek <jwiencek3@comcast.net> wrote:

> I have a three node cluster using streaming replication configured as
> follows:
> One synch node and one asynch node.
> If my synch node is down the master node is hung until that node is brought
> back on line.
>
> Two questions:
> 1.  Is this the expected action on my master?  It makes sense if it is since
> the master is waiting for an ack from the synch node.

Yes, when synchronous_commit = on, the default values that you should
have, the master will wait from standby the confirmation that the WAL
record for the commit has been flushed;
http://www.postgresql.org/docs/devel/static/runtime-config-replication.html#RUNTIME-CONFIG-REPLICATION-MASTER

> 2. Is there anyway to configure my cluster so I have a synch node but not
> have my master node “HANG” if the synch node is down?

You can do that at transaction level for example by disabling
synchronous_commit.
Regards,
--
Michael


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