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13016 - Cost Based Optimizer for DB2/400

13016 - Cost Based Optimizer for DB2/400

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Cost Based Optimizer for DB2/400

It depends.
Taking a look at just this one metric is not enough. Is the table
the index advised for also the table that shows up in the "50
slowest queries"? Or is it one that shows up in the "Table scans"
a lot? How about # index advised as compared to other tables?
What are the longest transactions? Which are the most used? Often
several of these factors need to be combined to make intelligent
changes. There is a lot of art (along with some science) to doing
detailed performance analysis. If you look at just a couple of
things, you only see a couple of things...and maybe miss something
important.
Ron

--- In DoNotReply@consolut.eu, "Klaus Lindegaard (RI)"
<klaus.lindegaardZr...> wrote:
> What would you consider as high 1000, 10000 or????
>
>
>
> Best regards
>
> Klaus
>
>
>
> -----Oprindelig meddelelse-----
> Fra: Satid Singkorapoom [mailto:satidZt...]
> Sendt: 24. februar 2004 08:54
> Til: DoNotReply@consolut.eu
> Emne: Re: Cost Based Optimizer for DB2/400
>
>
>
> Using ST04 --> Detail Analysis Menu --> Index Advice, try to see
if there
> are very high counts on "Index Advice Count" column (after sorting
this
> column in descending order). If so, drill down to see the SQL
> statement with the highest index advice count and start creating
> indexes as advised in the detailed information (the bottommost
> information field) to see if there is any run-time improvement.
It will be=
>
>
> good if U can recognise whether the table name with the highest
index
> advice count is related to any particular query that appears to
have run-
> time performance issue.
>
> Satid S.
> IBM Thailand
>
> --- In DoNotReply@consolut.eu, sumanjit_chowdhuryZi...
> wrote:
> > Hi Group,
> > We are on Kernel patch 1604 and at the Latest PTF level,
in SM50
> > almost all the programs are seen as performing Sequential Reads
> which is
> > affecting performance very badly i want to know how does the
> Optimizer
> > works for DB2/400 if it also uses CBO then it should also
access the
> Table
> > Access Statistics , i want to know how to check whether table
access
> > statistics are getting generated or not is there any job
scheduled to
> > update the statistics ..etc..
> >
> >
> > Any help on this...
> >
> > Thnks nd Regds,
> >
> > Sumanjit
> >
> >
> >
> >
> >
> > __
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