alter system set db_cache_size - reduce SGA
DBAsupport.com Forums - Powered by vBulletin
Results 1 to 5 of 5

Thread: alter system set db_cache_size - reduce SGA

  1. #1
    Join Date
    Sep 2000
    Location
    Chicago, IL
    Posts
    316

    Unhappy

    I executed the following command on our Oracle 9.2.0 RACed database on Compaq TRU64 Unix:

    Reduced db_cache_size from 1008M to 608M:

    alter system set db_cache_size = 629145600 scope=both sid='dbx2';

    The db_cache_size did get reduced, but I did not see any memory freed to the o/s - does thit not happen instantaneously ??

  2. #2
    Join Date
    Sep 2000
    Location
    Chicago, IL
    Posts
    316
    Anyone with this new 9i feature knowledge ?

  3. #3
    Join Date
    May 2002
    Posts
    2,645
    Don't you still have sga_max_size to contend with? Try forcing that down (or up) and you will see a difference.

  4. #4
    Join Date
    Sep 2000
    Location
    Chicago, IL
    Posts
    316
    What does the max_sga_size have to do with reducing the allocated memory. Plus, if I can do this dynamically, why do I have to mess with max_sga_size, which is static ?

    Here is another example:
    SQL>show sga

    Total System Global Area 3157237096 bytes
    Fixed Size 736616 bytes
    Variable Size 2097152000 bytes
    Database Buffers 1056964608 bytes
    Redo Buffers 2383872 bytes

    SQL>alter system set shared_pool_size=268435456 scope=both sid='dbx1';

    System altered.

    SQL>show sga

    Total System Global Area 3157237096 bytes
    Fixed Size 736616 bytes
    Variable Size 2097152000 bytes
    Database Buffers 1056964608 bytes
    Redo Buffers 2383872 bytes

    No change, why ???

  5. #5
    Join Date
    May 2002
    Posts
    2,645
    I had shared_pool sizing problems with 9i when using what used to be a good value for sga_max_size on an 8i database. I did all kinds of alter system this and that for sga components (different pool parameters). show sga didn't reflect any changes. Looking at v$sgastat should show your change.

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