Re: replication

On 8/6/2004 1:55 PM, Joshua D. Drake wrote:
> Hello,
>
> The two main replication products available are:
>
> Slony-I and Mammoth Replicator.
>
> Slony-I: Open Source, trigger based, batch replication.
>
> Mammoth Replicator: Closed Source (source license available), integrated
> (no triggers), live and batch replication.

Out of curiosity, what is the difference between live and batch
replication?

Slony-I has shown recently that it can achieve replication lags down to
a second average, with sporadic spikes up to several seconds on packet
loss in a WAN setup. That was replicating to a virtual machine running
on a notebook and the DB connections ssh-tunneled over two wireless
links and the internet ... not exactly what one would call a production
grade network connection. The server was running a TPC-W ordering mix at
that time, processing about 60,000 transactions per hour resulting in
15,000 row updates per hour (the PHP session data was DB-based and
replicated too). A 10 hour fallback of the replica (the slave system was
moved from Philadelphia to Toronto and back a weekend later :-) ) was
cought up in 3 hours against the continuously running main server over
the WAN, and in about 1.5 hours back in the WLan.

>
> They are both good solutions (I work for the creators of Mammoth
> Replicator) that serve different purposes.

Right (and I am the initial creator of Slony-I). Slony-I as a pure
trigger based approach for example does not aim at fully automatic DDL
replication.


Jan

--
#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me.                                  #
#================================================== JanWieck@Yahoo.com #