Ühel kenal päeval, E, 2006-08-21 kell 21:46, kirjutas Fujii Masao:
> Stefan Kaltenbrunner wrote:
> > It is however async replication so you can loose data commited on the
> > master but not yet replicated to the slaves in case you loose the master
> >  completely.
> Yes, here is an insufficient point of Slony-I, i think.
> Most systems will not permit the committed data to be lost, so use is limited.

But any sync _replication_ system will have severe impact on
performance. My guess is that for a full sync replication, going from 1
server to 2 will actually lower performance andsome small gains would be
possible only starting from 3rd server. 

This has nothing to do with postgreSQL, but is just due to latencies of
memory, disk and network and the need to do remote locking.

My quess is based on using standard 100Gb ethernet. It may be possible
to do better on some more advanced interconnects like myrinet.

Hannu Krosing
Database Architect
Skype Technologies OÜ
Akadeemia tee 21 F, Tallinn, 12618, Estonia

Skype me:  callto:hkrosing
Get Skype for free:  http://www.skype.com

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