Jeff Frost wrote:
> On Tue, 14 Nov 2006, Bruce Momjian wrote:
>
> >> My thinking on the definition of clustering was that there is some smarts for
> >> graceful failover and automated or semi-automated ways of bringing failed DB
> >> servers back up to date and online with the rest of the servers in the
> >> cluster. All servers need to be able to accept writes, but do we
> >
> > No, even replication servers can have that.
> >
> >> differentiate on where the writes originated (i.e. middleware or another
> >> postgresql server) or on functionality?
> >
> > Fundamentally, broadcast means the queries are being propogated outside
> > the server, with the benefits and limitations inherent in that.
>
> I'd definitely have to agree with you on that. I guess I'm trying to decide
> what differentiates clustering for load balancing from query broadcast based
> on your text. Maybe just don't use the word broadcast here:
>
> "In clustering, each server can accept write requests, and these write
> requests are broadcast from the original server to all other servers before
> each transaction commits."
>
> Unfortunately, I can't seem to come up with anything more clever.
Basically, when you are broadcasting outside the server, you are
broadcasting SQL queries, and those queries do not have information
about non-deterministic functions and have issues with universal commits
on all node.
I think I now see your point about using the word "broadcast" for both
clustering and middle-ware broadcast. Let me find some new wording and
repost.
--
Bruce Momjian bruce@momjian.us
EnterpriseDB http://www.enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +