Re: replication/synchronisation

Hey Chris
On Thu, 2006-09-07 at 18:38 -0400, Chris Browne wrote:
> glenn@tangelosoftware.net (Glenn Davy) writes:
> > Hi All - now heres a stupid question...
> > for better or worse a lot of project 'documentation' (wikis et.al.)  and
> > project administration occurs in web applications. A lot of my time is
> > spent for example in either trac or media wiki - and in my case these
> > nearly are always in a postgres backend.
> >
> > Unfortunately I can no longer just check out the latest documents and
> > take em off line on my laptop, edit them and merge them back later any
> > more.
> >
> > so obviously I want to take my laptop with a snap shot of the database,
> > (and wiki software etc) work on it, then synchronise it back to the
> > 'master'.
> >
> > My question (finally) is: are the existing tools for that purpose - are
> > pgpool or pgcluster or slony suitable? I'm tempted to try and script it
> > myself, but am apprehensive about manging id clashes primarily, and of
> > course managing rows updated in >1 db instance - and whatever else I
> > havent even though of
>
Thanks for replying

> Unfortunately, the "usual suspects" are generally designed to work
> when systems are connected more or less all the time.
>
yep - thats true
> Furthermore, what you're after seems to be one of the forms of
> "multimaster" replication,
yes that would make sense

>  which is the tougher problem that generally
> isn't supported.
>
 just wondering what you mean by 'generally'?
> In effect, what you're trying to do is akin to what PalmOS and Lotus
> Notes solve using synchronization systems.  There aren't any tools I
> can readily point you to to help do this with PostgreSQL, alas.
ok thanks - Im wondering how microsoft access and mssql server seem to
achieve this so easily - it seems to be tied up with that massively long
alpha unique row id (uid?) i wonder if adding  similar fields (ensuring
uniqueness could prove interesting) to all tables in any given schema
and triggers or rules to maintain them would allow provide a basis for
some sort of simple system? Im clearly out of my depth here - just
puzzled why it seems so doable in some platforms and nigh impossible on
others.
I guess im wondering if there is something intrinsic to postgres that
makes this idea prohibitive, or is it that developers already have hands
full with other features on their minds?

glenn