This discussion is archived
5 Replies Latest reply: Feb 11, 2013 8:25 AM by Victor Armbrust RSS

RAC and sequences

JOE_humble Newbie
Currently Being Moderated
Grid/RDBMS Version : 11.2.0.3 on RHEL 5.4

One of our application team doesn't want to move to RAC as they are INSERT intensive application and when they did a testing/POC back in 2003 with Oracle Parallel Server they had issues with Sequences.

Can I tell them that its safe to move to 11.2.0.3 RAC and you won't face issues with sequences ?
  • 1. Re: RAC and sequences
    Hesh Newbie
    Currently Being Moderated
    I guess you can get some help here...

    http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:1816824600346180435
  • 2. Re: RAC and sequences
    JohnWatson Guru
    Currently Being Moderated
    My experience of this is that any problem in a RAC would have been a problem single instance, too. However, some things that you can get away with single instance MUST be fixed in a RAC.
    An example of the first is the sequence issue: contention for a well designed sequence will be no worse in a RAC than single instance. If scalability is a problem in one environment, it will be a problem in the other.
    An example of the second is ASSM. Freelist contention is bad single instance, and it may be worse in a RAC. Therefore conversion to ASSM should be on your to-do list as part of the move to RAC. But then, it should be on the list anyway.
    --
    John Watson
    http://skillbuilders.com
  • 3. Re: RAC and sequences
    Victor Armbrust Oracle ACE
    Currently Being Moderated
    That's always a good question. Rac and sequences has a seriosly content do discuss..

    I always try to use NOCACHE + NOORDER as mentioned on the MOS NOTE: ID 853652.1 The default is CACHE + NOORDER and has the least performance impact on RAC.
    HOwever, each app has your own characteristcs to use sequence, so the best way is always take the subject with the app team.

    Victor
  • 4. Re: RAC and sequences
    JohnWatson Guru
    Currently Being Moderated
    >
    I always try to use NOCACHE + NOORDER as mentioned on the MOS NOTE: ID 853652.1 The default is CACHE + NOORDER and has the least performance impact on RAC.
    Victor, this has yo be a typing error: NOCACHE is disastrous for single instance, even worse in a RAC. Always cache, and cache a lot: the default of 20 is too low, got for a 200000 perhaps if you are issueing millions a day.
  • 5. Re: RAC and sequences
    Victor Armbrust Oracle ACE
    Currently Being Moderated
    Yes... sorry.. CACHE + NOORDER....
    thanks

    :D

Legend

  • Correct Answers - 10 points
  • Helpful Answers - 5 points