Replication solutions with Oracle 8i

Question

Hello,
I'm looking for solutions to make real time replications from an Oracle 8i database.
For more details :
- we have an existing database with Oracle 8i
- we want to replicate this database: the replicated database will be used by a web application.
- we need the replication to be in real-time
For the moment i didn't find much informations on the web and it seems that replication solutions for the version 8i are quiet limited.
If someone have any idea on how i can do this, it would be helpfull.
Thanks,

Answer 1

Among the problems, though, is that there are numerous ways to architect a replication process. That architecture requires you to make various trade-offs. Without understanding what you're attempting to gain in a business sense from the replication process, though, it's impossible to even attempt to figure out which trade-offs to make.
One option would be to create a new database for the reporting app and create a fast-refreshable materialized view in the reporting database for every table in the source system. In the source system, you'd then create materialized view logs on every table in the source database. If you want the reporting system to be transactionally consistent, you'd need to put the various materialized views into one or more refresh groups and schedule those refresh groups to run every 5 minutes.
That would probably get close to having data on the reporting system within 10 minutes of it being created on the source system. The downsides, though, would include
- Every transaction on the source system now needs to synchronously write to the materialized view logs. This is roughly equivalent to creating a new trigger on every table in your system, which can be a decent load.
- The reporting system will have to poll the source system for data changes every few minutes. That's likely to put a pretty decent load on the source system.
- Making DDL or large DML changes to the source requires the source system admins to be conscious of the destination system's needs (the destination system's materialized view may need to be recreated and an initial full refresh may need to be done which may impact the timing of the change on the source system).
- The source system admins (and the destination system admins) have to monitor the refresh process, the size of the materialized view logs, etc.
- Spreading information across multiple systems increases the liklihood of improper data disclosure because you have less ability to figure out who has access to any particular piece of data, for example.
For a reporting application, I'm really hard pressed to imagine that these downsides are worth whatever benefit you're trying to achieve.
Justin