Re: Replication

AgentM wrote:
>
> On Aug 21, 2006, at 15:00 , D'Arcy J.M. Cain wrote:
>
> >On Mon, 21 Aug 2006 14:46:05 -0400
> >"Gregory Maxwell" <gmaxwell(at)gmail(dot)com> wrote:
> >>On 8/21/06, Alvaro Herrera <alvherre(at)commandprompt(dot)com> wrote:
> >>>But the confirmation that needs to come is that the WAL changes have
> >>>been applied (fsync'ed), so the performance will be terrible. So
> >>>bad,
> >>>that I don't think anyone will want to use such a replication
> >>>system ...
> >>
> >>Okay. I give up... Why is waiting for fsync on a fast local network
> >>which takes 15us to send a message (infiniband is cheap..) an
> >>unimaginable delay when we tolerate a local 8ms fsync delay on
> >>systems
> >>without writeback cache?
> >
> >OK, that solves your problem. How about my problem where replication
> >has to happen on servers in three countries on two continents and
> >thousands of updates a second have to happen in less that 10ms?
> >This is
> >the critical issue with replication - one size does not fit all.
> >Syncronous replication, in particular, fits almost no one.
> >
> >My experience is that any replication needs to be based on your
> >business
> >rules which will vary widely.
>
> Sure- and more specifically, replication rules may differ on every
> table according to those rules. The current solutions are on/off for
> a list of tables. I wonder if the various pgsql replication engines
> have any problems co-existing...

Althought I have never tried, I am sure Mammoth Replicator could
coexist relatively sanely with Slony-I.

--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.