Re: clustering factor and uniqueness

"yoram.ayalon_at_structuredweb.com" <yoram.ayalon_at_structuredweb.com> wrote:
> thanks for the answer.
>
> >>So is that 13M values with one row each and 1 value with 4M rows?
> >>Or is it 9M values with 1 row each and 4M values with 2 rows each?
>
> its the second scenario. most values have 1 row, some values have a low
> number of rows, less than 10 is the norm.
>
> >>That would depend on the query
>
> I am using a very simply query.
>
> SELECT * FROM TABLE WHERE X = value;
>
> X is the field indexed, VARCHAR2(9). my test query returns 4 rows

What is the explain plan for it?

Is value a varchar2? Maybe type conversion is preventing effective use of the index.

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