Dictionary Cache Hit Ratio
DBAsupport.com Forums - Powered by vBulletin
Results 1 to 4 of 4

Thread: Dictionary Cache Hit Ratio

  1. #1
    Join Date
    Jun 2001
    Posts
    243
    I ran the following scripts..

    SELECT parameter, gets, Getmisses,
    getmisses/(gets+getmisses)*100 "Miss Ratio",
    (1-(sum(getmisses)/ (sum(gets)+sum(getmisses))))*100 "Hit Ratio"
    FROM v$rowcache
    WHERE gets+getmisses <>0
    GROUP BY parameter, gets, getmisses;


    and I got the following results...

    Miss Ratio Hit Ratio
    ---------- ---------
    20 80
    1.25 98.75
    19.13 80.87
    .9925 99.01
    24.99 75.01
    1.058 98.94
    .3995 99.6
    8.012 91.99
    23.08 76.92
    26.32 73.68
    17.49 82.51
    33.33 66.67
    .6425 99.36
    .5745 99.43
    3.448 96.55
    .377 99.62

    Can you explain what's going on with the results?....


  2. #2
    Join Date
    Oct 2000
    Location
    Saskatoon, SK, Canada
    Posts
    3,925
    Refer this doc, before you start doing the things with tuning.

    http://www.oradoc.com/ora816/server.816/a76992/toc.htm


    Sam
    Thanx
    Sam



    Life is a journey, not a destination!


  3. #3
    Join Date
    Jun 2001
    Posts
    87
    Hit is the number of times a statement is requested and it is found in the cache. A Miss is when it is requested and not found in the cache.

    For Rowcache the most important hit ratios to consider are dcobjects and dcsysnoyms. The sum of misses to gets should be less than 15%.

    Maybe this link will be of some help. Check it out.

    http://www.ecst.csuchico.edu/~melody...tune_stats.htm


  4. #4
    Join Date
    Oct 2000
    Location
    Saskatoon, SK, Canada
    Posts
    3,925
    That reference was a good one!

    Sam
    Thanx
    Sam



    Life is a journey, not a destination!


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