Re: cluster replication with intermezzo

Tom Lane <tgl@sss.pgh.pa.us> writes:
> Robert Williams <bob@bob.usuhs.mil> writes:
> > I don't thing this should be a problem,
> > since as I understand it, table and row
> > locking occurs at the postgres backend level
> > and lock files are kept in a database table,
>
> No, the locking is all done in shared memory.  Since you've got two
> postmasters with two separate shared memory blocks, there is no
> interlocking between the two sets of backends.

Speaking of which, I vaguely recall the OpenMOSIX guys talking about
possibly implementing clusterable shared memory (i.e. "shared" across
machines in a cluster) at some point in the future. There would still
be some problems with using PostgreSQL in that environment (e.g. the
different semantics between NFS and normal filesystems), but it's an
interesting possibility, at any rate.

Cheers,

Neil

--
Neil Conway <neilc@samurai.com> || PGP Key ID: DB3C29FC