Re: [Postgres-xc-general] Move from a single-cluster machine to a multi cluster machine.

[Mason S. <ms...@tr...>]

On Thu, Aug 21, 2014 at 3:04 PM, Joseph Mays <ma...@wi...> wrote:

>   Okay, I have a postgres-xc “cluster” operating with only one machine in
> the cluster. What I want to do is load the database from the standard
> postgres cluster into it, then switch over to make it operational as the
> postgres server. Then I want to rebuild the original standard postgres
> machine to be another postgres-xc cluster machine and add it as a second
> machine to the cluster.
>
>  There are still several things about this I have to figure out, but one
> question I don’t know the answer to is how I bring the two machines into
> “sync” at the database. Is there some way to add the second machine into
> the cluster and have it synchronize its database to the first machine in
> the cluster, or do I have to dump the database, get them running in a two
> machine cluster with a blank database, and the restore the dump into the
> two machine cluster?
>
>  If the latter, if one machine goes down or something, so that the other
> is carrying all the load for a bit, how I do bring the two machines back
> into sync when the failed machine comes back up?
>
>

It sounds like you are trying to minimize downtime while you switchover.

If you were running on PostgreSQL 9.4, this may have been easier with the
help of logical streaming replication. In the meantime, you may want to use
a trigger-based scheme or Slony, where you enable triggers to track the
changes, dump the data, load into XC and then play back those changes that
were captured.

Regarding adding the other server back, if the load can handle it, you
could already define it as a datanode and have data be loaded there. If you
have a spare system and recent version of PostgreSQL, you could use
streaming replication to it, promote it to being the master, then configure
the other two systems.

Regards,


-- 
Mason Sharp

TransLattice - http://www.translattice.com
Distributed and Clustered Database Solutions