i think confusion between IN and LIKE, anyway, i rarely use IN.




2009/12/23 Ann W. Harrison <aharrison@...>

> >> Fernando Medeiros wrote:
> >>> where afield = id
> >>> if the afield is indexed, the performance is better.
> >>>
> >>> where afield in (id)
> >>> the performance is same (low) with field indexed or not.
> >>>
> >>> correct me if i am wrong.
> >> Sorry, but the optimizer will use an index for IN - both
> >> formats of IN - list of values and select statement.
> >>
>
> What I should have said is that for reasons having to do with
> the handling of null values of afield (I think) NOT IN is
> optimized differently - and badly. So IN does use indexes,
> but NOT IN won't always - maybe never. If you can live with
> the difference between NOT IN and NOT EXISTS, use the latter.
>
>
> Cheers,
>
> Ann
>
>
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