Re: Query failing in CBO mode

All other things being equal (and there
are a couple of pages in the performance tuning guide outlining some things that
are not equal - like joins conditions, indexed columns, subqueries, user-defined functions etc.) the 'final' predicates against a single table are evaluated from the bottom up under RBO and from the top down under CBO.

Everything is subject to change, of course - so if you are using cpu_costing in version 9 you may already have discovered that Oracle will ignore the above and re-arrange the order of the 'final' predicates against a single table to minimise the CPU cost of evaluating them.

In your case it appears that the RBO eliminates the problem rows because none of them get through the last two predicates:

          PROJECT_ORDER = 'Y'
    and ORDER_STATUS ='O'

Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

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The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: 26 February 2003 05:18

> I have an application query that runs fine in RBO mode but failing
in CBO with ORA-01722: invalid number -
>
> select /*+ rule */ ORDER_NO,ITEM_NO
> from SCHED_RECEIPTS_at_db01.world
> where ORDER_NO = 4432089
> and PROJECT_ORDER = 'Y' and ORDER_STATUS ='O'
>
> ORDER_NO ITEM_NO
> ---------- --------------------
> 4432089 TOOLING COSTS
>
> 1 row selected.
>
> select /*+ choose */ ORDER_NO,ITEM_NO
> from SCHED_RECEIPTS_at_db01.world
> where ORDER_NO = 4432089
> and PROJECT_ORDER = 'Y' and ORDER_STATUS ='O'
>
> ERROR:
> ORA-01722: invalid number
> ORA-02063: preceding line from DB01.WORLD
>
> no rows selected
>
> ORDER_NO column is varchar2 field and it may be containing some
non-numeric data, so I understand that Oracle may be doing implicit conversion on order_no. But, then why it is working fine in RULE based. The explain plan is same in both cases and is using FULL Table access. The table has unique index on ORDER no.
>

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Jonathan Lewis
  INET: jonathan_at_jlcomp.demon.co.uk

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