Re: nonunique index on unique values

On Aug 28, 3:22 pm, ciapecki <ciape..._at_gmail.com> wrote:
> hi,
>
> is there a big lost in performance if there is a nonunique index on
> the column that holds only unique values (like primary key)?
>
> thanks
> chris

If you mean a nonunique index, compared to a unique index, is used to enforce a unique constraint, there's performance penalty in terms of generated redo when you get error ORA-1 (unique constraint violated). See
http://orafaq.com/papers/oracle_redo_generation_wp.pdf

Yong Huang Received on Wed Aug 29 2007 - 10:34:33 CDT