Hello Bruce,

You wrote:
I am still feeling that data partitioning is like master/slave
replication because you have to get that read-only copy to the other
server.


Yes, that's where replication comes into play. But data partitioning per se has nothing to do with replication, has it? You can partition your data however you want: among tablespaces, among databases or among multiple servers. Data partitioning solves different problems than replication. I think it's important to keep them separate. Why do you mix-in Slony-I in the Data Partitioning Section? One can use any other replication solution to "get that read-only copy to the other server".

If you split things up so data sets resided on only one
machine, you are right that would not be replication, but do people do
that?  If so, it is almost another solution.

Yes, as I say: Data Partitioning solves another problem.

And for
multi-master, Oracle RAC is clearly multi master,
Yes.

 and I can see pgpool
as multi-master, or as several single-master systems, in that they
operate independently.
Several single-master systems? C'mon! Pgpool simply implements the most simplistic form of multi-master replication. Just because you can access the single databases inside the cluster doesn't make it less Multi-Master, does it?

OK, changed to "Multi-Master Replication Using Query Broadcasting".

Good. That reads already better for me. ;-)

As Jim Nasby pointed out in [1], not all solutions are as simplistic as pgpool and do not necessarily have the same disadvantages - while using the very same algorithm: Query Broadcasting.

I suggest we make sure to clarify that and better point out some of the aspects all Multi-Master Replication have in common (see replication_doku_4.diff of my patches).

Added.

Added.

(the additions to "Shared Disk Failover")

Good. Short and clear. (Except perhaps: how can I find out if NFS has full POSIX behavior? Do we have to go into more detail there? I dunno.)

Uh, but the locks are the same on each machine as if it was a single
server, while in a cluster, the locks are more intertwined with other
things that are happening on the server, no?

Sure.

Maybe you are right and we should better not use the term locking there. It seems confusing because it's not clear what a 'lock' is for some replication systems (i.e. also Postgres-R, how do you compare it's "amount of locks"?).

Regards

Markus

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