Re: Upgrading cluster with thousands of DBs

On Tue, Jan 14, 2014 at 11:45:33AM +0100, Alejandro Martínez wrote:
> Hi list,
>
> We're working on upgrading from 9.1 to 9.3 some of our database
> clusters, while seeking to minimize (write) downtime by making the
> upgrades as fast as possible.
>
> However, our clusters have the particularity that they get to host
> many different *databases*, as in, ~2000 databases per cluster. Most
> of those databases are small (only a table and PostGIS functions), so
> it's more a problem of the number of DBs than the space they use. The
> total size of the cluster is around 60gb.
>
> I first started using pg_upgrade but, even when enabling
> parallelization and hardlinks, as most of the steps (preliminary
> check?) don't seem to be parallelized, the upgrade takes ~5 hours as
> it goes database-per-database serially on most steps.

That is surprising.  I know I see parallel hard link creation and
parallel database dump in my testing of 9.3 pg_upgrade.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + Everyone has their own god. +