On 09/11/2011 09:27 AM, Claudio Freire wrote:
I have used slony to do database migration. It is a pain to set up, but it saves you hours of downtime.
I've had to shoot this option down in two separate upgrade scenarios in two different companies. Theoretically it's possible, but slony is based on triggers. If you have an OLTP database with frequent writes, that overhead (firing the trigger, storing the replicated data, reading the replication log, traffic to the upgrade node) can literally kill your application. Downtime is one thing, but maintenance windows can be planned. Ruining application performance for an undetermined length of time is probably worse.
Thankfully 8.4 added pg_migrator/pg_upgrade, so that kind of pain is probably over for the most part. But even without it, 8.4 and above have parallel restore, which can drop upgrade times down to a fraction of their former length.
-- Shaun Thomas OptionsHouse | 141 W. Jackson Blvd. | Suite 800 | Chicago IL, 60604 312-676-8870 sthomas@xxxxxxxxx ______________________________________________ See http://www.peak6.com/email-disclaimer/ for terms and conditions related to this email -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
