Tuning your table design

Your application program is the largest factor in determining the efficiency of data access. However, there are some things you can do to make it easier for a program to access the data. For example:

• When multiple data types can be used to represent the domain of a column, use the most appropriate one (make each row as short as possible, thus ensuring that the table occupies as few pages as possible).
  • Use SMALLINT rather than INTEGER where appropriate.
  • Use the DATE and TIME data types rather than CHAR.
  • Use NOT NULL for columns wherever possible.
• Choose data types that can be processed most efficiently.
  • Use CHAR rather than VARCHAR for any narrow columns (for example, those that are less than 50 characters wide).
  • Use FLOAT rather than DECIMAL for columns if exact precision is not required.