Message-ID: <48ADABAF.8030602@drivefaster.net>
Date: Thu, 21 Aug 2008 11:53:51 -0600
From: Dan Harris <fbsd@drivefaster.net>
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To: pgsql-performance@postgresql.org
Subject: The state of PG replication in 2008/Q2?
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My company finally has the means to install a new database server for 
replication.  I have Googled and found a lot of sparse information out 
there regarding replication systems for PostgreSQL and a lot of it looks 
very out-of-date.  Can I please get some ideas from those of you that 
are currently using fail-over replication systems?  What advantage does 
your solution have?  What are the "gotchas" I need to worry about?

My desire would be to have a parallel server that could act as a hot 
standby system with automatic fail over in a multi-master role.  If our 
primary server goes down for whatever reason, the secondary would take 
over and handle the load seamlessly.  I think this is really the "holy 
grail" scenario and I understand how difficult it is to achieve.  
Especially since we make frequent use of sequences in our databases.  If 
MM is too difficult, I'm willing to accept a hot-standby read-only 
system that will handle queries until we can fix whatever ails the master. 

We are primary an OLAP environment but there is a constant stream of 
inserts into the databases.  There are 47 different databases hosted on 
the primary server and this number will continue to scale up to whatever 
the server seems to support.  The reason I mention this number is that 
it seems that those systems that make heavy use of schema changes 
require a lot of "fiddling".  For a single database, this doesn't seem 
too problematic, but any manual work involved and administrative 
overhead will scale at the same rate as the database count grows and I 
certainly want to minimize as much fiddling as possible.

We are using 8.3 and the total combined size for the PG data directory 
is 226G.  Hopefully I didn't neglect to include more relevant information.

As always, thank you for your insight.

-Dan