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  1. #1
    Join Date
    Nov 2007
    Location
    Athens, Greece
    Posts
    22

    Unanswered: Sort_sequence may cause performance issues?

    It started with this post here: http://www.dbforums.com/db2/1700669-...w-console.html

    I have 4 AS400s running JDEdwards.

    Lately a performance issue occured as described in the above link.

    Although i am not an expert in AS400 , i tried to find out the cause. I think it came down to this:

    I run the following SQL in all my systems:

    Code:
    select sort_sequence,index_schema,count(*) from qsys2.sysindexstat group by sort_sequence,index_schema
    In 3 of my 4 systems all of them have sort_sequence="BY HEX VALUE"

    In my 4 problematic system many indexes have sort_sequence="*LANGIDSHR"

    I start to believe that this can cause performance problems as the query optimizer may leave these indexes unused and create temp indexes.

    I wish somebody has an idea on where to go on from now and how.

    Is there any specific setting that make all the indexes have default sort_sequence?

    All my indexes are created massively so this could not happen by mistake.

  2. #2
    Join Date
    Nov 2007
    Location
    Athens, Greece
    Posts
    22

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