Re: Re: how to get oracle to ignore an index

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Fri, 6 Feb 2004 19:12:13 -0000
Message-ID: <008d01c3ece5$3c1d1270$6702a8c0@Primary>

Notes in-line

Regards

Jonathan Lewis
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Original Message ----- From: <ryan.gaffuri_at_cox.net> To: <oracle-l_at_freelists.org> Sent: Friday, February 06, 2004 6:28 PM Subject: Re: Re: how to get oracle to ignore an index

i cant reproduce the data for you. its internal. I tested it repeatedly. I was very careful about the hint.

select /*+ index(<index_name>) */

>>> The thing above is not a valid hint

select /*+ index(<table> <index_name>) */

>>> The thing above might not be a valid hint
>>> as the <table> might have been given an alias
>>> If the table does not have an alias, then this
>>> will be obeyed, unless some conditions relating
>>> to null columns could make the indexed path
>>> return the wrong path, or (prior to skip scans)
>>> there was no optimizer mechanism for using
>>> the index.

Tried it repeatedly. I've seen it before. Sorry, I cant show you the data, etc... I could have swarn I read in the docs that hints are just directives and oracle does not have to use them? I cant find it right now. Am I wrong? I'm pretty sure I have seen that several times.

>>> There are some bugs relating to execution methods
>>> that require some detailed examination of 10053
>>> trace files to determine how Oracle pushed an
>>> 'obvious' hint out of context. Apart from these,
>>> and there are some 'feature-related' hints that
>>> can only work if various init.ora parameters
>>> are set ... and so on.
>>>
>>> You probably have read that hints are 'just'
>>> directives (to me a directive is the same as
>>> an order, by the way). I've seen it in a Metalink
>>> note somewhere. You will have found numerous
>>> articles which say that hints can be ignored.
>>> But in recent versions I don't think I've been
>>> presented with an example where a valid hint
>>> was ignored.
>>

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Received on Fri Feb 06 2004 - 13:12:13 CST