how to improve the performance?

elibs

how to improve the performance?
Hello,list:
My DB2 for OS390 has hold about 1000 tables and many of those have rows up to 40M.These large tables are devoted to being inserted and updated.As the size of the tables increase,the batch jobs run more and more slow.Is there anything to improve the performance except to create index the tabels?

Thanks
Larry

tim malamphy

Re: how to improve the performance?
(in response to elibs)
You may want to review how you think an index is going
to improve your writes to DB2. Generally, an index
will help for reading data, but SLOWS down updating
and inserts. There's an extra I/O that has to be done
as each index gets updated. An old batch tuning trick
is to drop all the indexes before beginning a massive
update/insert job, then rebuild/recover the index(es)
after that job has completed, and before the indexes
are needed by the applications doing lots of reads.
Since you're only updating about 200K records, I doubt
if it would be worth your while to rebuild all your
indexes for 40M rows, but you could certainly test it.
Try to whittle down the number of indexes to as few as
possible.

Have you tried to monitor the job and see where it's
spending most of it's time? There's a whole bunch of
things that could be going on.

--- elibs <[login to unmask email]> wrote:
> Hello,list:
> My DB2 for OS390 has hold about 1000 tables and
> many of those have rows up to 40M.These large tables
> are devoted to being inserted and updated.As the
> size of the tables increase,the batch jobs run more
> and more slow.Is there anything to improve the
> performance except to create index the tabels?
>
> Thanks
> Larry
>


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