Re: Replication

Glen,

It really depends which technologies you intend to use. If you are going to use read-only snapshots, then this is a reasonably robust and tried technology. As the name suggests, these allow you to distribute copies of data aound the network but they are only updateable at the master site. All other sites see a "recent" copy - how recent depends on how you configure it.

The more advanced replication stuff has been (in my experience) a bit buggy and difficult to administer. Snapshots can be made updateable (though they still have a central master site) or tables can be fully replicated (multi-master) between sites. The full replication, sometimes refered to as "n-ways" replication can either be asynchronous (deferred) or synchronous (within the commit unit).

With multi-master replication you have to decide what to do when a conflict is encountered -- two users updated the same row at about the same time. Oracle supply some resolution routines or you can write your own.

Before embarking on any of these technologies, you need to assure yourself that you really do need it. The only reason for distributing data is to put it closer to the users who own it and require access to it for purposes of performance. Any gains in performance come at a significant cost in terms of complexity and administration.

Regards

Ian Stevenson

co-author of Oracle Design: The Definitive Guide - to be published shortly by O'Reilly & Associates "Glen Self" <glen_at_comclin.com> wrote:
>We are considering Oracle for our main database system.
>How tight and robust is the consistancy of replication on Oracle servers?
>Thanks for any assistance.
>Glen
>glen_at_comclin.com
Received on Tue Dec 10 1996 - 00:00:00 CST