From: Bruce Momjian <bruce@momjian.us>
Message-Id: <200611142254.kAEMsBK02780@momjian.us>
Subject: Re: [HACKERS] Replication documentation addition
In-Reply-To: 
 <Pine.LNX.4.64.0611141446390.23695@discord.home.frostconsultingllc.com>
To: Jeff Frost <jeff@frostconsultingllc.com>
Date: Tue, 14 Nov 2006 17:54:11 -0500 (EST)
CC: Chris Browne <cbbrowne@acm.org>, pgsql-docs@postgresql.org
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Jeff Frost wrote:
> On Tue, 14 Nov 2006, Bruce Momjian wrote:
> 
> >> 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.
> >>
> >> I guess it's kind of a fine line how it gets defined?
> >
> > Hmmm.  Interesting.  Does anyone else have details or an opinion on
> > this?  The fact that there is something sitting above the servers seems
> > to be the defining issue of calling it query broadcast.
> 
> 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.

-- 
  Bruce Momjian   bruce@momjian.us
  EnterpriseDB    http://www.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +