Result from v$rowcache
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Thread: Result from v$rowcache

  1. #1
    Join Date
    Mar 2001
    Posts
    77
    I ran the UTLBSTAT and selected the view v$rowcache. now, can someone please tell me what do these data represent? Thank you!!

    SVRMGR> SELECT parameter, gets, getmisses
    2> FROM v$rowcache;
    PARAMETER GETS GETMISSES
    -------------------------------- ---------- ----------
    dc_free_extents 147 32
    dc_used_extents 23 23
    dc_segments 117 45
    dc_tablespaces 106 3
    dc_tablespace_quotas 0 0
    dc_files 0 0
    dc_users 76 8
    dc_rollback_segments 126 4
    dc_objects 558 109
    dc_global_oids 0 0
    dc_constraints 4 3
    dc_object_ids 302 50
    dc_synonyms 7 4
    dc_sequences 3 2
    dc_usernames 64 5
    dc_database_links 0 0
    dc_histogram_defs 8 4
    ...

    I tried to make it easier to read, but it doesn't come out the way I wanted. Please bear with me. Tks.

  2. #2
    Join Date
    Aug 2001
    Posts
    111
    From the Oracle doco...
    "v$rowcache: This view displays statistics for data dictionary activity.
    Each row contains statistics for one data dictionary cache. "

    This view shows the information which can be used to calculate the hit ratios for each area of the data dictionary cache.

    Here are some links to various doco on both dictionary cache and utlbstat/utlestat

    Tuning memory allocation: Ch19 of Oracle doco :
    http://technet.oracle.com/docs/produ...2/ch19_mem.htm
    Utlbstat/Utlestat
    http://www.adsinc.com/whitepapers/UtlestatReport.html

    Rule of thumb bad hit ratios may be a symtom of either a
    1) too small shared pool
    2) frequently used stored procedure not pinned.
    3) Too much parsing i.e lack of bind variables.

    Have Fun
    Performance... Push the envelope!

  3. #3
    Join Date
    Aug 2001
    Location
    Waterloo, On
    Posts
    547
    I would suggest u gather Aggregates instead of individual parameters from V$ROWCACHE.


    SELECT SUM (GETS-GETMISSES)/SUM (GETS) * 100 AS HIT RATIO FROM V$ROWCACHE;

    Hit ratio for dictionary cache should be 85% or higher.If its low, you need to address the problem. I suggest tuning the Library Cache first.

    (PS: You should collect data only after your database has been running for quite sometime).

    I dont think you need to run UTLBSTAT to gather data from V$ROWCACHE view. Utilities like UTLBSTAT (followed by UTLESTAT) collect data from these dynamic performance views.

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