Re: RULE or COST based???

"Stephan" <test_at_test.com> wrote in message news:<1S0p9.542306$2I.17732081_at_nlnews00.chello.com>...
> Let me tell you a little story.
> I started developing a forms application on Ora 7.3.4.
> There was 1 simple instance whit NO settings voor RULE/CBO or other.
> I just created the tables, did NO analyze and developed Oracle FORMS
> against it.It worked well and fast.
>
> The application was ready and implemented at different customers, each with
> there own database.
> (versions ranging 7.3.4 to 8i).
> (from our instance export to a dump file, created a new instance at
> customers Oracle databases
> and imported the dump there)
> No problem.All customers experience(d) good response of database.
>
> One customer, running Oracle 8.0 on Unix, did create the instance for us.
> We also imported the dump and now the response is slower and slower every
> day at that instance.
> I did make a dump of customers database and imported in a 8i NT Oracle
> database in our office.
> An what happens? The forms are slow!
> I did do some SQL_TRACE and TKPROF and EXPLAIN_PLAN.
> I saw many FULL .. SCANS so I decided to remove ALL statitiscs (dbms_utility
> ... 'delete') from
> database. The Forms now run FAST, except form some queries.
>
> So my question: did I develop RULE BASED?
> Do you have suggestions according to above story?

If there is any analyze done on any table in a query, the CBO will be invoked. (See the Oracle Performance Tuning Manual). Depending on optimizer_mode.

You might consider requiring it to be set to rule in the init.ora.

jg

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