Re: Oracle Hint Behavior
Date: Sat, 2 Feb 2008 11:11:39 -0000
"Dereck L. Dietz" <dietzdl_at_ameritech.net> wrote in message
> Oracle 10.2.0.3.0
> Windows 2003 Server
> What is the behavior of hints in Oracle 10g? I knew that prior to 10g
> Oracle would treat them as only "suggestions" but I thought in 10g they
> would be mostly followed.
> We have a query which is doing a full table scan even with hints being
> used to try to get it to use an index. I can see why it would choose a
> full table scan considering the percentage of the table being returned
> but I'd like to be able to explain why the hint is being ignored now.
One of the problems of hinting in 10g is that the rules of application seem to have become more formal. This MAY be a side effect of the way that cost-based query transformation works.
I have examples where I can supply hints that are considered correct in 9i, but are not valid unless I use the fully qualified hint with the query block name included.
-- Regards Jonathan Lewis http://jonathanlewis.wordpress.com Author: Cost Based Oracle: Fundamentals http://www.jlcomp.demon.co.uk/cbo_book/ind_book.html The Co-operative Oracle Users' FAQ http://www.jlcomp.demon.co.uk/faq/ind_faq.htmlReceived on Sat Feb 02 2008 - 05:11:39 CST