Null Values

Defining columns as NULL or NOT NULL helps the optimizer work more efficiently.

Specifying NULL or NOT NULL allows the optimizer a more educated guess at joins and search criteria by having one more piece of information about the characteristics of the data. NULL data does not save space on the database page, as it would in other databases. NULL data will, however, be compressed out when stored on disk due to the IQ compression algorithms and optimized indexes.

• Always specify NULL or NOT NULL

• Open Client and ODBC connections have different default behavior when table is created

• Give the optimizer an additional piece of information about the characteristics of the data for joins and search arguments