Re: Replication

Well Oracle replication does work. There are a lot of if's and but's regarding things like data types and versions of Oracle. I was a bit miffed to discover that DIFF and RECTIFY tools don't support LOB's, I suppose since they appear to be mostly written in PL/SQL I should have guessed....

Is 128Kb/s enough - well you can make replication work over that. The main question is how much data is being transferred. If you have no updates Oracle doesn't try and push it, and so replication works fine over virtually no bandwidth at all. Remember for replication Oracle pushs the old and new values (in many cases you can reduce this) so build in a fair margin for error.

Always allow for upgrades, and sorting out issues, when sizing the bandwidth.

The big crunch is not how to set it up. The manuals are pretty clear - Replication manager is also great - at least for figuring out what is happening.

The big issue is can the application use replication. You can use Synchronous replication with a lot of applications. But this is effectively keeping both copies of the relevant objects identical. Lose the network link, and you lose the ability to update these objects. Worse still you must wait for a commit to take place on both the local and remote server - often defeating the performance gain you get by using replication.

Most people want to use asynchonous replication, here you must ensure that the logic of your application will fit with replication. Do you for instance issue deletes against a table that you want to replicate? Not necessary impossible with asynchronous replication, but it can be fun.

Each component of replication is fairly straight forward, but put together it can make a considerable challenge. I'd say find someone who has done both the programming, and support side of Oracle replication before (ideally several times), and discuss through what you are trying to achieve.

It may be you can achieve your goals with a few 'read only snapshots' - in which case you are laughing. It may be what seemed like a simple idea, is actually a major rewrite of the application.

    Simon

Franz Mueller <nospam#####franz.mueller_at_orbis.de> wrote in message news:388341ee.32362594_at_news.salink.net... Hi,

[Quoted] I need to replicate to distant servers that are connected by a 128kB line. It should keep both servers almost identical. There will be DB updates on both servers.
Does this work properly? Is 128kB enough? How do I set it up?

Thank you
Franz Received on Mon Jan 17 2000 - 00:00:00 CET