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  1. #1
    Join Date
    Oct 2009
    Posts
    14

    Unanswered: Interpreting db2evmon

    Hello,

    We are using db2 v8.1 FP17 on AIX 5.1.

    We have db performance issue, so i set the event monitor for statements and tried executing a simple select count(*) query.

    Even though the query was executed only once, but in log (o/p of db2evmon) it shows 4 entries for the same query!
    The value for "Operation" feild in log is "Prepare", "Open", "Describe" snd "Close".

    Is it a normal behaviour? or somthing is going wrong?

    Also The "execution time" for last entry 18 sec, I think it is more.[note: The count of records in this table is 5336191]


    Please help me if you have any information on this.


    Thanks for your time

  2. #2
    Join Date
    Aug 2008
    Location
    Toronto, Canada
    Posts
    2,367
    Quote Originally Posted by DB Guide

    Even though the query was executed only once, but in log (o/p of db2evmon) it shows 4 entries for the same query!
    The value for "Operation" feild in log is "Prepare", "Open", "Describe" snd "Close".

    Is it a normal behaviour? or somthing is going wrong?

    This is normal. Queries executed from CLP (dynamic) will show prepare/open/describe/close.

  3. #3
    Join Date
    Oct 2009
    Posts
    14
    Thank You Bella.

    One more question from me... How can i go ahead with performace issue? i tried getting execution time for queries. it is around 60-70 Seconds on avg. i don't know if it is normal for these queries.

    How can i determine if i requre sql tunning or bufferpool tunning or cfg tunning or something else?

    Can you suggest any important weblink on this?

  4. #4
    Join Date
    Aug 2008
    Location
    Toronto, Canada
    Posts
    2,367
    I think no one can answer your question if 60-70 sec is normal for these queries on this forum... the answer would be "it depends".

    I find a lot of helpful performance related info on this DB2 forum. Some people (Marcus_A for example) have provided really good info on how to tune bufferpools/queries/etc so search the forum.

    I personally like the following performance related docs:
    IBM Redbooks | DB2 UDB ESE V8 non-DPF Performance Guide for High Performance OLTP and BI
    ftp://ftp.software.ibm.com/ps/produc.../db2d3e951.pdf


    You can also search google for optimizer related articles written by Samir Kapoor from IBM.

  5. #5
    Join Date
    Oct 2007
    Posts
    246
    do a reorg and runstats on the tables in the queries,
    what is size of the table if its huge, check with explain plan
    whether index is been used or not, create proper indexes
    and check
    regds
    Paul

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