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Presuming the system is running in 'CHOOSE' mode
the cost based optimiser works out that the 'cost' of the query by Full Table Scan is cheaper than by index.
Regards
--
Kevin A Lewis (BOCM PAULS LTD - Animal Feed Manufacturer - Ipswich England)
<KevinALewis_at_HotMail.com>
The views expressed herein by the author of this document
are not necessarily those of BOCM PAULS Ltd.
Frank Calfo <fcalfo_at_psateam.com> wrote in message
news:01beb34e$41603e40$e401010a_at_FRANK...
> I'm doing a simple test on index usage:
>
> I have a table, Employee, with the columns: empid,
> name,
> type
>
> I have a simple query: select * from employee where type = 4 ;
>
> When I run an execution plan on this statement it indicates that
> Oracle will do a full table scan on the employee table.
>
> This is as expected
>
> I then add a nonunique index to the table consisting of only the type
> column
>
> I run statistics on the schema with the estimate option
>
> Then I rerun the execution plan with this same query
>
> It still indicates Oracle will do a full table scan on the table.
>
> Why won't Oracle use the index?
>
> Thanks.
>
>
Received on Thu Jun 10 1999 - 10:36:41 CDT