question on v$system_event
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Thread: question on v$system_event

  1. #1
    Join Date
    Nov 2002
    Posts
    31

    question on v$system_event

    I have question about stats from v$system_event. i just checked on one of db

    SELECT EVENT,AVERAGE_WAIT
    FROM V$SYSTEM_EVENT
    WHERE EVENT LIKE 'db file s%';

    EVENT AVERAGE_WAIT
    db file sequential read 1159.27
    db file scattered read .15

    are these stats okay ?
    table scans are cheaper v/s index scan or i am reading it wrong

    thanks gc

  2. #2
    Join Date
    Jun 2000
    Location
    Madrid, Spain
    Posts
    7,447
    not enough to say anything

    you need to get delta values, not values since instance was brought up (which is what v$system_event shows)

  3. #3
    Join Date
    Nov 2002
    Posts
    31
    I have statspack running.

    just queried the statspack table.

    SNAP_ID EVENT TOTAL_WAITS
    856 db file scattered read 18367608
    856 db file sequential read 15646602
    857 db file scattered read 18367635
    857 db file sequential read 15668088
    858 db file scattered read 18367705
    858 db file sequential read 15793211
    859 db file scattered read 18367739
    859 db file sequential read 16854095


    i checked with writer of

    http://www.evdbt.com/SearchIntelligenceCBO.doc ( Very GOOD Article )

    since async io is turned on ! the stats i am seeing might be wrong

    any other thoughts
    thanks

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