The entire EAV database model has been homogenized. Since each column's value is kept in a separate data type table, joining five or six different tables is necessary even if you only need one piece of information. Columns in EAV are referred to as characteristics. A flat model just makes use of one table. It takes up more database space and is not normalized. It is not a viable solution for dynamic requirements where you could need to add extra columns down the road. Its performance is quick because it simply requires one query rather than joining five to six tables. Columns are referred to as fields in a flat form.