Re: Index on Primary Key

A primary key is unqiue by definition. The RDBMS checks uniquness by looking for a matching key in the table and the most efficient way to do this check is to use a unique index. Note it doesn't have too, but could use a table scan. This is obviously only efficient for tables with a small number of rows. As indexes for small tables are also a small overhead the default action is to always create them. Thank goodness.

Actually the real reason is to reduce the number of mails posted to this news group. Could you imagine the number of mails we would get stating that loads get proportianatly slower as they add more rows. :o)

Snow Tracks wrote:

> If I use ERwin to build an Oracle schema, its default behavior is to index
> the primary key.
>
> Any have any thoughts/experience with an index on the primary key?
>
> Thank you,
> st
Received on Thu Apr 22 1999 - 02:46:44 CDT