It depends. B-Tree index access is only more efficient than a full table
scan for systems that have many different values. Thus it is unlikely that
creating a conventional index for tables with low cardinality is a good
idea. However Oracle does have an index type that is suitable for such
data,provided that it is rarely (ideally never) updated. This is the bitmap
index. The exact threshold for index acccess being more efficient than table
scans will vary according to your data.
--
Niall Litchfield
Oracle DBA
Audit Commission UK
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"dbuckingham" <member_at_dbforums.com> wrote in message
news:3d3bb349$1_at_usenetgateway.com...
> Is it better to apply indexes to tables that have many different random
> values or is it better to apply to tables that only have a small number
> of values (large table but a lot of the same value)?
>
> Dan.
>
>
>
> --
> Daniel Buckingham
> Technical Consultant
> Mercia Software
>
> Posted via dBforums
> http://dbforums.com
Received on Mon Jul 22 2002 - 03:07:20 CDT
