| Stopping optimizer choosing concatenation [message #522198] |
Wed, 07 September 2011 04:36  |
Roachcoach
Messages: 1576
Registered: May 2010
Location: UK
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Senior Member |
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Hi,
I have a feeling the answer is 'not easily' but google thus far is failing me (or I need better google-fu).
I've got an operation where the optimizer is taking a concatenation path and I want to test it's performance by forcing it to not take this path and deal with it as a standard 'or'.
Is there a (presumably undocumented since I can't find reference to it) hint to force it not to? I'm aware of the USE_CONCAT() hint, but there seems to be no way to force-prevent concatenation.
Does anyone have any ideas on how I can prevent it using concat (other than maybe re-writing the query in a different fashion)?
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