Re: Sync Replication with transaction-controlled durability

On Tue, 2010-09-14 at 18:48 +0100, Simon Riggs wrote:

> I'm working on a patch to implement synchronous replication for
> PostgreSQL, with user-controlled durability specified on the master. The
> design also provides high throughput by allowing concurrent processes to
> handle the WAL stream. The proposal requires only 3 new parameters and
> takes into account much community feedback on earlier ideas.

I'm now implementing v5, which simplifies the parameters still further

USERSET on master
* synchronous_replication = off (default) | on
* synchronous_replication_timeout >=0 default=0 means wait forever

set in postgresql.conf on standby
* synchronous_replication_service = on (default) | off

WALwriter is not active, nor are multiple sync rep modes available.
Coding allows us to extend number of modes in future.

Coding also solves problem raised by Dimitri: we don't advertise the
sync rep service until the standby has caught up.

This patch is a rough WIP, mostly stripping out and streamlining. It
doesn't work yet, but people say they like to see me working, so here
'tis.

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