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Re: Replication accross a WAN

From: Peter Sylvester <peters_at_mitre.org>
Date: Thu, 21 Oct 1999 10:23:30 -0400
Message-ID: <380F21E2.85D551B8@mitre.org>


There are a number of 3rd party solutions out there, none of which is perfect, but which might be better than what you're willing to write.

To make the sequences unique you can configure each machine with a different starting number and increment by the maximum number of machines (ever) expected. Then each machine will generate unique sequence numbers.

I believe the above is documented in Oracle's Replication Manual, which you should dig into.

You may run into issues with doing SQL*Net over low bandwidth if your update rates are high.
You should consider running some test cases.

Peter

Dave Waterworth wrote:
>
> Hi
>
> Could anyone point me towards resources detailing standard Oracle techniques
> for replicating accross a low(ish) bandwidth wide area network. We want to
> keep two databases in synch. Synchronous replication is not critical, but
> replication must be bi-directional (i.e. inserts on db1 replicated to db2
> and inserts on db2 replicated to db1 simultaneously). Are there robust, cost
> effective commercial packages available? Is it more effective to write your
> own scheme based on expert knowledge of the schema and applications?
>
> Currently the proposal is to write our own. One things that's bugging me is
> that the data in each database is meant to be identical, including fields
> that are modified by triggers, (setting last modified field to sysdate,
> primary key to a sequence numver etc.). But how do you keep the sequences in
> step? If sequence is initially in step and a different record is inserted at
> each site, the different records will end up with the same sequence number?
>
> Any comments will be appreciated
>
> Dave Waterworth
>
> Power Systems Consultants New Zealand Ltd
Received on Thu Oct 21 1999 - 09:23:30 CDT

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