Re: adding a bdr node using bcv backup

On 21 January 2016 at 08:29, (Daniel Stolf) <dstolf(at)gmail(dot)com> wrote:

> Hello there...
>
> I'm new to postgres and I'm trying out BDR replication...
>
> I know that when I issue the bdr.bdr_group_join command, it will copy the
> entire database from the host I specify on parameter 'join_using_dsn' and
> this may take a while depending on the network and the size of the
> database...
>
> What I wanted to know is if I can leverage a bcv backup... Is it possible?
>

BCV seems to be an EMC backup system. It looks like a snapshot. If the
snapshot taken is consistent and atomic, and if it includes both pg_xlog
and the rest of the datadir and all tablespaces in the SAME snapshot taken
at the SAME instant, then you can treat it much like a pg_basebackup. In
that case you can use bdr_init_copy to bring it up as a new BDR node. You
must either stop all writes to all other nodes or pre-create the
replication slots *before* taking the snapshot though, otherwise the new
node won't be able to catch up to writes done after the snapshot and before
it was started.

If this sounds too complex then stick to the documented methods that work.
Working from separately taken snapshots is hard to get right and could lead
to subtle data problems if you get it wrong.

--
Craig Ringer http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services