Re: Replication and PITR

Csaba Nagy wrote:
>>> Cons:
>>>
>> - No reliability. On slow days, WAL logs could take a long time to
>> rotate, so small but important transactions might not be replicated
>> for a long time.
>>
>
> That's gone with 8.2, it will be possible to stream the last
> modifications, or force a WAL recycle periodically, whatever fits you
> better. There is some new infrastructure which allows these things,
> although I didn't have the time to play with them.
>
Keep in mind that while Slony-I provides you with a read-only replica
(able to service queries). At present WAL log replication (in 8.2 or
otherwise) would allow you to have a 'warm standby' type database -
which would be somewhat in sync (pending the latest transactions), but
would be unable to service queries (essentially, you'd have a server
that was sitting with postmaster in a recovery state).

Chander Ganesan
Open Technology Group, Inc. - Expert PostgreSQL Training
One Copley Parkway, Suite 210
Morrisville, NC 27560
Phone: 877-258-8987/919-463-0999
http://www.otg-nc.com

> The big improvement would be indeed to have the infrastructure to start
> up a standby by simply pointing it to the master server, no other setup
> needed. Implement that, make it reliable, and any beginner to postgres
> will be able to easily set up a WAL shipping based standby. Right now
> you still have to do some complicated scripting to make it work (no idea
> how much 8.2 will help here, didn't try yet).
>
> Cheers,
> Csaba.
>
>
>
>
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