One-to-One Relationships

Take a final look at the entities. If you find a one-to-one (1:1) relationship between two tables, you might be better off collapsing them into one table. However, maintaining a 1:1 relationship could improve response speed in queries. For example, if you have information about titles that you seldom use (notes on copyright information, lists of change pages, for example), you might want to keep it in a separate table so that you don't have to access the information when running common queries. Generally speaking, you should avoid 1:1 structures when you first design a database, unless you know your data very well.