One-way or Two-way

In a database the relationship exists in both directions

e.g. for a given salesperson you can find the clients they have sold to, and for a given client the salesperson who served her

Finding this information requires a database join - takes time

If you only want to go one way - e.g. store to salesperson, but don't need the list of sales people who work at a store

use EOM to add the store relationship to the salesperson entity, but don't add the reverse relationship

improves performance by removing unnecessary joins

Page updated September 7, 2004