On 04/22/2010 10:12 AM, Ben Chobot wrote:
On Apr 21, 2010, at 1:41 PM, Brian Peschel wrote:

I have a replication problem I am hoping someone has come across before and can 
provide a few ideas.

I am looking at a configuration of on 'writable' node and anywhere from 10 to 
300 'read-only' nodes.  Almost all of these nodes will be across a WAN from the 
writable node (some over slow VPN links too).  I am looking for a way to 
replicate as quickly as possible from the writable node to all the read-only 
nodes.  I can pretty much guarantee the read-only nodes will never become 
master nodes.  Also, the updates to the writable node are bunched and at known 
times (ie only updated when I want it updated, not constant updates), but when 
changes occur, there are a lot of them at once.
Two things you didn't address are the acceptable latency of keeping the 
read-only nodes in sync with the master - can they be different for a day? A 
minute? Do you need things to stay synchronous? Also, how big is your dataset? 
A simple pg_dump and some hot scp action after you batched updates might be 
able to solve your problem.

Latency is important. I would say 10 to 15 minutes max, but the shorter the better. I don't have an exact size, but I believe the entire DB is about 10 gig.

We had an idea of creating our apps write the SQL statements to a file, rather than using an ODBC drive to directly change the DBs. Then we could scp/rsync the files to the remote machines and execute them there. This just seems like a very manual process though.

- Brian

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