Plan stability

Hi,

my question is about the same, but more general. How can i force Oracle to use my prefered way of explain plan and not use CBO's. I mean, apart from stored outlines, it somehow seems to complicated. I would like to say what order and join types it should use. But, try as I might, I many times cannot force Oracle to use my way, even though I know it is possible, for I saw this kind of explain plan for that specific query..

I tried to use hints like ordered and use_hj etc. Can someone give some examples of full set of hints for some simple queries?

Thx,
rw

> Hi, list friends:
> We are using partition to archive history data in our
> production OLTP database. We get great performance gains(Far
> less disk io), but we also hit performance trouble sometimes.
> So I am here ask for your experience.
>
> We used local index on all partitioned tables.We add/drop
> partition monthly to archive the history data.
>
> But the trouble is, when add/drop partition is being done
> on the partitioned table, CBO sometimes changed SQL execution
> path.We implemented partition 2 monthes ago, and in the first
> time, add/drop partition went on quite smoothly, but in the
> second time we add/drop partition, two SQL (just TWO SQL) get
> bad execution path and server load rushed to 10 times(from 2
> to 20 in uptime), all waiting for latch free event. It
> severely affected our application. We are an online system
> and we do not have scheduled time every month so we have to
> add/drop partition while db is still running.
>
> So, with system still up and running, how do you add/drop
> partition without changing the SQL execution path? We do not
> have the time to reanalyze/dbms_stats the tables ,analyze
> takes hours and if SQL execution path changed, during these
> time, system is nearly unusable.
>
> I tried to import old
> statistics(dbms_stats.import_table_stats), but did not fix
> the problem.
> So, can you share your experience on managing partitioned table?
>
> Regards
>
> Zhu Chao
> www.cnoug.org
>
>
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net

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Author: Wartiak Rastislav
  INET: RWartiak_at_cpoj.cz

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