Oracle Streams on a Rac Environment

Question

Hi
I have some questions with respect to Setting up Streams on a rac Environment.Would appreciate a quick response as I need the answers by tommorrow.Any help would be greatly appreciated.Here are the questions
1> Do we have to create capture process for each active instance on only 1 capture process will do?
2> If yes then do they need to have a seperate queue for each one?
3> How will the apply process access multiple capture process and the propogation take place?
4> can only 2 tables in the source be replicated instead of the entire database?
5> In case if we use a push job if both the primary and secondary go down how can we move to the third instance and use it?
6> If the instance goes down do we have to restart the capture process once again?
7>What is the best suited for rac - ASM/RAW FILES with respect to Streams?
Regards
Shweta

Answer 1

Streams in 9iR2 RAC environment mines only from archive logs not online redo logs. This restriction is lifted in 10g RAC. If you choose to go thru the downstream capture route in 10g then you can only mine from archive logs in 10gR1.
Having said the above here are my answers:
1> Do we have to create capture process for each active instance or only 1 capture process will do?
You can run multiple capture processes each on difference instance in RAC. Unless you have a requirement to do so, a single capture process would suffice. The in-memory queue should also be on the same instance as the capture process is running from.
2> If yes then do they need to have a seperate queue for each one?
YES
3> How will the apply process access multiple capture process and the propogation take place?
Propagation is from a source queue to the destination queue. If the destination is a single instance database, then you can direct propagations for all of your capture(s) into a single apply queue. If the destination is also RAC then you can run multiple apply processes on each node and apply changes for specific set of tables. Maintenance would be something to think about here along with what happens when one node goes down.
4> can only 2 tables in the source be replicated instead of the entire database?
YES. Streams is flexible to let you decide what level you want to replicate.
5> In case if we use a push job if both the primary and secondary go down how can we move to the third instance and use it?
In theory propagation is a push job. There are certain things you need to configure correctly. If done, then you can move the entire streams configuration to any of the surviving node(s).
6> If the instance goes down do we have to restart the capture process once again?
In 9iR2 you have to restart the streams processes. In 10g the streams processes automatically migrate and restart at the new "owning" instance. In both versions, Queue ownership is transferred automatically to the surviving instance.
7> What is the best suited for rac - ASM/RAW FILES with respect to Streams?
Streams is independent of the storage system you use. I cannot think of any correlation here.