7 Replies Latest reply: Jul 17, 2008 4:31 PM by PhilipRN-Oracle RSS

    Sequences under RAC

    218022
      Does anyone have any general/specific recommendations for the 9300 sequences in EBS under RAC?

      Jeff
        • 1. Re: Sequences under RAC
          218022
          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?

          Jeff
          • 2. Re: Sequences under RAC
            ErikP
            Jeff:
            I thought there was a metalink doc, but cannot find it. I am asking others to get details.
            -Erik
            • 3. Re: Sequences under RAC
              ErikP
              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.
              • 4. Re: Sequences under RAC
                dba-india
                My recommendation is to disable caching of sequences for production database.

                Sami Malik
                • 5. Re: Sequences under RAC
                  413311
                  Could you tell us why ? caching sequence (noorder) is the best way to reduce sequence performance problem in rac !!!
                  • 6. Re: Sequences under RAC
                    580716
                    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
                    • 7. Re: Sequences under RAC
                      PhilipRN-Oracle
                      Sami Malik's response does not seem correct - cached sequences will perform better