FAQ
Gurus ...

A single tablespace/datafile is showing a huge increase in phys
reads since the end of March. The numbers are:

DATE PHYRDS READ_PCT PHYWRTS WRITE_PCT

Mar 22 3,863 0.21 651 0.23
Apr 28 5,985,597 76.84 757 0.12

All other datafiles show just minor variation. Most are at less than
1% for read and write pct, and the few that do have higher physical
read or writes are the major players in the application, but still remain
below 3 % for datafiles, and between 3 to 5% for the index files. I have
checked and all the indexes are still in place and the schema has been
analyzed nightly (compute) This tablespace holds 6 frequently used
but smaller tables. No changes on the server except that the SA updated
firmware. DB hit ratio has nosed dived from approx. 95% to 75%, but
the problem appears to be confined to this tablespace. SGA settings
have not been changed.

Any suggestions on what to investigate next would be appreciated!!

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  • Jared Still at Apr 29, 2000 at 12:01 am
    My first inclination would be to find out what is
    affected by the firmware change the SA made.

    Next I would monitor v$sess_io to catch the account(s)
    causing all the physical reads, and then collect their
    SQL from the v$sqltext and run it all through explain plan.

    Someone or something is likely doing some queries that
    are either new, or the execution plan has changed to
    a change in statistics.

    Jared
    On Fri, 28 Apr 2000 rsands_at_lendleaserei.com wrote:



    Gurus ...

    A single tablespace/datafile is showing a huge increase in phys
    reads since the end of March. The numbers are:

    DATE PHYRDS READ_PCT PHYWRTS WRITE_PCT
    Mar 22 3,863 0.21 651 0.23
    Apr 28 5,985,597 76.84 757 0.12

    All other datafiles show just minor variation. Most are at less than
    1% for read and write pct, and the few that do have higher physical
    read or writes are the major players in the application, but still remain
    below 3 % for datafiles, and between 3 to 5% for the index files. I have
    checked and all the indexes are still in place and the schema has been
    analyzed nightly (compute) This tablespace holds 6 frequently used
    but smaller tables. No changes on the server except that the SA updated
    firmware. DB hit ratio has nosed dived from approx. 95% to 75%, but
    the problem appears to be confined to this tablespace. SGA settings
    have not been changed.

    Any suggestions on what to investigate next would be appreciated!!

    TIA
    Robyn


    --
    Author:
    INET: rsands_at_lendleaserei.com

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    Jared Still
    Certified Oracle DBA and Part Time Perl Evangelist;-)
    Regence BlueCross BlueShield of Oregon
    jkstill_at_bcbso.com - Work - preferred address

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postedApr 28, '00 at 7:40p
activeApr 29, '00 at 12:01a
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