Persisting Messages in Buffered Queues

Question

Hello Everyone,
As per the oracle documentation http://docs.oracle.com/cd/B28359_01/server.111/b28321/strms_prop.htm#i1006905
LCRs that were captured by a capture process are always stored in a buffered queue, but LCRs that were captured by a synchronous capture are always stored in a persistent queue.
This means that if we use Capture process and server goes down( or is restarted), we will loose those messages in buffered queues as messages are stored in memory.
1) Is there a way to force capture process to persist the message into persistent queue?
2) Is there a way to recover the messages from buffered queue when we restart the server?
Please let me know if you have some ideas / some insights for above two cases.
Thanks
Nithin
Edited by: 906226 on Jan 5, 2012 11:20 AM

Answer 1

Hello,
This is really a Streams question.
When the database goes down the buffered messages are lost. However when the instance restarts the Capture re-mines the redo logs from the required_checkpoint_scn and then re-enqueues the LCRs. The apply also keeps track of where it was at via the apply progress So nothing is lost in the Streams scenario when an instance goes down. This is discussed in the documentation.
In the AQ world if you are using a buffered queue then the messages would be lost and the application would have to handle that situation.
Thanks
Peter