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Thread: X$KCBCBH and X$KCBRBH

  1. #1
    Join Date
    Mar 2002
    Posts
    171
    Dear firends,

    I am not able to see the tuning tables X$KCBCBH and X$KCBRBH having logged in as SYS. Any reason why I am not able to see them? Please help, I am using Oracle 8i.


  2. #2
    Join Date
    Feb 2001
    Location
    Bombay,India
    Posts
    530
    Hi,
    The two tables x$kcbcbh and x$kcbrbh are not in use anymore. They have been discontinued from Oracle 8i.

    Regards,
    Rohit Nirkhe,Oracle DBA,OCP 8i
    oracle-support@indiatimes.com
    Thanks and Regards
    Rohit S Nirkhe
    rohitsnirkhe@rediffmail.com

  3. #3
    Join Date
    Jun 2001
    Location
    Hyderabad
    Posts
    18
    i think v$current_bucket ,v$recent_bucket will fulfil ur needs

  4. #4
    Join Date
    Mar 2002
    Posts
    171
    Ramesh: Unfortunately, I couldn't find even those tables you have mentioned.

    ROHIT: Thanks for the info. Then if these tables are discontinued, how do we tune the Database Buffer??

    I mean, how do we calculate ACH (Additional Cache Hits) -that would occur for each query and transaction for the buffer increments we make - to tune the Database Buffer??

    Kindly help me resolve this question.

  5. #5
    Join Date
    Mar 2002
    Posts
    171
    Strange, no one to answer this Q :-) Pls help.

  6. #6
    Join Date
    Jun 2001
    Location
    Hyderabad
    Posts
    18
    yeah ur right as i said those tables are in oracle 8 and those tables are obsolete in 8i. as far as i know to tune the database buffer keep increasing the buffer till u reach the hit ratio. once u wont find any hike in hit ratio that will be the right size for db buffer

    rameshchitturi@rediffmail.com
    rams

  7. #7
    Join Date
    Feb 2001
    Posts
    389
    From oracle8i the alogrithm for dirty buffer , LRU list , DBWR acitivity has changed for better.
    I believe they are forcing us to use multibple buffer pools , then using v$buffer_pool_statistics,
    x$bh u can find out which objects are for what pool and then get the statistics from v$buffer_pool_statistics u get the tuning information.

  8. #8
    Join Date
    May 2000
    Posts
    50
    Use STATSPACK. This provides with all the info that was previously provided by X$KCBCBH and X$KCBRBH.

  9. #9
    Join Date
    Sep 2001
    Location
    NJ, USA
    Posts
    1,287
    For using V$BUFFER_POOL_STATISTICS u should execute script :
    $ORACLE_HOME/rdbms/admin/catperf.sql, because this view is not create by default.

    About X$KCBCBH and X$KCBRBH :
    some information that was in that tables u can get from new X$ tables:
    X$KCBWBPD - buffer pool descriptor and X$KCBWDS.


  10. #10
    Join Date
    Mar 2002
    Posts
    171
    Originally posted by Shestakov
    For using V$BUFFER_POOL_STATISTICS u should execute script :
    $ORACLE_HOME/rdbms/admin/catperf.sql, because this view is not create by default.

    About X$KCBCBH and X$KCBRBH :
    some information that was in that tables u can get from new X$ tables:
    X$KCBWBPD - buffer pool descriptor and X$KCBWDS.


    Thanks for the response. Indeed the tables X$KCBWBPD and X$KCBWDS have some info in common.


    One more last question:
    ===============
    ===============


    With the X$KCBCBH and X$KCBRBH tables -

    ACH (Additional Cache Hits) was calculated as
    select sum(count) "ACH" from x$kcbrbh where indx < 100;

    and

    ACM (Additional Cache Misses) was calculated as
    select sum(count) "ACM" from x$kcbcbh
    where indx >= (select max(indx)+1-100 from x$kcbcbh);



    Any idea how do we get these values with the tables X$KCBWBPD and X$KCBWDS.

    I would appreciate your answers.




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