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Apparently there is an EBS/RAC Performance doc on Metalink that answers this question. I don’t think I have ever come across it. Does anyone know the DocID?
I thought there was a metalink doc, but cannot find it. I am asking others to get details.
OK I checked into more detail on this point.
The sequences that would have the greatest effect on performance should have already been optimized for RAC in the base EBS setup.
So the recommendation is when you are in production or running performance tests, to see if any of the sequences show up as bottlenecks, and if so open up a SR to see if these particular sequences have any restrictions.
Best of luck. If others have particular experiences it would be good to hear as well.
My recommendation is to disable caching of sequences for production database.
Could you tell us why ? caching sequence (noorder) is the best way to reduce sequence performance problem in rac !!!
In RAC environments, it is always suggested to cache the sequence number to avoid the concurrent updates on the data dictionary because of sequence generator. If cluster databse is processing heavy workload then database sessions may have to wait on SQ enqueues if sequences are not cached. If you want ordered sequence number then you can use 'CACHE ORDER' of sequence. If there is no such requirement of ordered sequence number then 'CACHE NORDER' is the best trade.
Thanks & Regards
-Harish Kumar Kalra
Sami Malik's response does not seem correct - cached sequences will perform better