Re: Indexes and Where clauses

From: Martin Smith <mfsmith_at_erols.com>
Date: 1997/08/02
Message-ID: <33E40DB1.A283DF5D@erols.com>#1/1

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This may be a good app for bit-mapped indexes, since they let you set up SEPARATE indexes on each column that are efficiently combined (in any combination) at run-time.
(Plus they are small and fast!)

Martin Jesterhoudt wrote:

> On 31 Jul 1997 22:31:09 GMT, jck4_at_msg.ti.com (Lilyan Jackson) wrote:
>
> >In order to ensure that an index gets used in a query, does the
 column is
> >position one of the index have to be in the where clause?
>
> In order to assure an index is used, you can use the following
> directive:
>
> select /*+ INDEX(<indexname>) */ .... <type the rest of your query>
>
> >INDEX_NAME COLUMN_NAME COLUMN_POSITION
> >----------- ----------- ---------------
> >INDEX1 KEY_1 1
> >INDEX1 KEY_2 2
> >
> >Will INDEX1 be used if only KEY_2 is specified in the where clause?
>
> No, because it has the second position in your indexkey.
> --------------------------------------------------------
> ----------------------
> --- Martin
> Jesterhoudt ---
> --- martinj(replace this by
> @)worldonline.nl ---
> ---------------------------------------------------
> ---------------------------

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--------------F976D6103A100D5F02E8EEB0-- Received on Sat Aug 02 1997 - 00:00:00 CDT