Hi Malcolm,
>From above question, I'd like to ask another question which related to
indexhint.
Let's say I need to query to tableA which field criteria is field1.
select * from tableA where tableA.field1 = _field1
indexs for table A are below
1. NumIdx
field1
field2
field3
2. ItemIdx
field1
field3
In best practice, which index should I use ?
Thanks and Regards,
Afin
On Wed, Aug 18, 2010 at 6:53 PM, Malcolm Burtt <
malcolm.bu...@touchstone.co.uk> wrote:
>
>
> Hi
>
>
>
> For most queries, the answer is to use neither.
>
>
>
> “Index Hint” overrides the SQL Query optimiser and forces the use of the
> specified index – which is ok if you’re sure that the optimiser is picking a
> bad query plan and that using “index hint” allows your query to run faster
> but most of the time the optimiser is better at picking the right index than
> you are so you should let it do its job. When you do need to tune the query
> you should consider other hints (e.g. forcenestedloop, etc) alongside “index
> hint” to get the most effective query plan for your data.
>
>
>
> I can’t think of a good reason to use “Index” at all. It simply ensures
> that the data is returned sorted in the index order which you can already
> achieve with the “Order By” clause with the important advantage that the
> sort order would not change if someone altered the index definition in some
> way.
>
>
>
> Regards
>
>
>
>
>
> Malcolm Burtt
>
> Touchstone Group
>
> People - Partnership - Solutions
>
>
>
>
>
>
>
--
ne faites pas une limite pour votre competence
-------------------------------------------------------------------------
bilden Sie nicht eine Begrenzung fur Ihre Fahigkeit
-------------------------------------------------------------------------
non faccia un limite per la vostra abilita
-------------------------------------------------------------------------
--(-@
