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How do we get solid numbers to determine how many physical writes a specific sql or pl/sql package will perform? When we use 10046 I believe it only gets physical reads because the dbwriter is asynchronous? I have some concerns about using AWR for this.

Also, how do we get reliable redo numbers? When I use set autotrace on and run the same insert multiple times the redo seems to vary by 20% or so.

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  • Stephane Faroult at Sep 13, 2006 at 7:53 pm
    Ryan,

    You cannot relate writes to one particular SQL statement since they
    are performed on a system-wide basis by dbwr and friends. Ditto with
    redo. I think that the best you can do it to take a snapshot of
    v$sesstat before and after your statement/package for the most relevant
    statistics. And even so, I fear that for regular block-writes it would
    not be very useful. Assume that you have several concurrent sessions
    concurrently updating the same data block. How will you render unto
    Caesar the things that are Caesar's?

    HTH

    Stéphane Faroult

    ryan_gaffuri_at_comcast.net wrote:
    How do we get solid numbers to determine how many physical writes a
    specific sql or pl/sql package will perform? When we use 10046 I
    believe it only gets physical reads because the dbwriter is
    asynchronous? I have some concerns about using AWR for this.
    Also, how do we get reliable redo numbers? When I use set autotrace on
    and run the same insert multiple times the redo seems to vary by 20%
    or so.
    --
    http://www.freelists.org/webpage/oracle-l

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postedSep 13, '06 at 7:40p
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