DBAsupport.com Forums - Powered by vBulletin
Page 1 of 2 12 LastLast
Results 1 to 10 of 16

Thread: rollback segment question

  1. #1
    Join Date
    Nov 1999
    Posts
    226
    Hi

    Should SYSTEM RB have an optimal value set like all other Rollback segments . Please let me know

    Thanks

  2. #2
    Join Date
    May 2002
    Posts
    2,645
    Oracle automatically creates the SYSTEM rollback segment and it can never be dropped. It is never listed in the init.ora file. So, no, there is no "optimal" size for it - it is managed by Oracle.

  3. #3
    Join Date
    Nov 1999
    Posts
    226
    Should I put an Optimal size for it , If I do what harm can I cause to the Database performace

    regards

  4. #4
    Join Date
    Jun 2000
    Location
    Madrid, Spain
    Posts
    7,447
    it will be never used after your database creation, why you wanna do that???

  5. #5
    Join Date
    May 2002
    Posts
    2,645
    Again, there is no optimal size for it - it is managed by Oracle. All you can do is sit back and watch.

  6. #6
    Join Date
    Nov 1999
    Posts
    226
    Some of my users had their default Tablespaces to system ,
    I was under the impression that if the default tablespace is system , it might use the "SYSTEM RB" for work

    I think I am wrong here .

    I get the point that the SYSTEM RB will never be used after DB creation .

    Please confirm my misunderstanding here

    Thanks a lot guys !!

  7. #7
    Join Date
    Oct 2000
    Location
    Charlotte, USA
    Posts
    330
    Yes You are mistaken........
    What is the error you are getting???.Meaning what kind of error made you to come to this conclusion....
    System rb is used only once at the time of db creation.Thats it.After that temp or what ever you name....rbs1,2,3...

    Your Users created without specifying default tablespace.
    Thats why default tablespace is SYSTEM.Better change their default tablespace from system.It is not a good practice.
    Thanks.
    Thanigaivasan.


  8. #8
    Join Date
    May 2002
    Posts
    15
    keep in mind that
    never let any application or users to user system tablespace,
    if you had, alter user default tablespace and quota immediately, and move all tables and indexes out of system tablespace, action now!
    Just wanna get more and more professional with oracle
    Just wanna a job relateed with oracle

  9. #9
    Join Date
    May 2002
    Location
    California, USA
    Posts
    175
    Originally posted by thanigai
    Yes You are mistaken........
    System rb is used only once at the time of db creation.Thats it.After that temp or what ever you name....rbs1,2,3...
    No quite right, Thanigai

    Here is how the rollback segment in the SYSTEM tablespace is used:

    When a database is first created using the CREATE DATABASE command, only a single rollback segment is created. This is the system rollback segment and it is created in the system tablespace. The system rollback segment has one basic difference from any other rollback segment, including any other rollback segments that are created in the system tablespace. This difference is that the system rollback segment can only be used for transactions that occur on objects inside the system tablespace. This is done because the main purpose of the system rollback segment is to handle rollback for DDL transactions - that is transactions against the data dictionary tables themselves. Making the system rollback usable only for the system tablespace was simply an easy way to enforce that. It is possible for the system rollback segment to be used for non-data dictionary tables, but only if those tables are created inside the
    system tablespace (which is very bad development practice).


    Rollback segment in the SYSTEM tablespace is not used only once at db creation, but for the life of the database. Actually, every time you do DDL on the data dictionary (running catproc.sql, catalog.sql, etc...).

    Check the latest Oracle DBA forums for more details:
    http://www.dbaclick.com/cgi-bin/ib3/ikonboard.cgi


    Hope that hopes,



    --clio_usa
    Senior Oracle DBA

  10. #10
    Join Date
    Feb 2000
    Location
    Singapore
    Posts
    1,758
    To clio_usa:

    Are you sure that DDL statements use rollback segment?

    Sanjay

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


Click Here to Expand Forum to Full Width