Re: all foreign key should have index?

On Tue, 31 Jan 2006 22:12:56 +0000, Eric Junkermann <eric_at_deptj.demon.co.uk> wrote:

[snip]

>When you delete a parent row, or update its key, the DBMS needs to find
>the children, either to cascade the operation or to forbid it - how can
>it do this efficiently without an index? But of course if you never do
>those things,
>you might still need it to find child rows efficiently anyway.

     Why does it have to be an index?

Sincerely,

Gene Wirchenko Received on Wed Feb 01 2006 - 14:06:03 CST