Re: dbmirror revisions

On Friday April 4 2003 3:41, nolan@celery.tssi.com wrote:
> > I think a consistent view on the slave during active replication is not
> > quite guaranteed with this approach.  Sequence updates are not
> > transactional, we really don't know how to order them with respect to
> > tuple updates.  So someone reading the slave DB might possibly not see
> > sequence changes appear in the order in which they occurred on the
> > master.  For our warm spare/slave needs, it appears adequate.
>
> Aside from problems dealing with the loss of the communications link,
> wouldn't it be better to implement a function call from the slave(s) to
> the master to query the master's sequence?  This can be done with
> pgperlu.

Why do you think that would be better?  It is already done in a perl
function that launches SQL ...

> If there are INDEPENDENT sequences on the master and the slave, what's to
> guarantee uniqueness?

Not sure I understand the question.  Uniqueness in what respect?

Ed