n is either 1 or 0. The default value is 1.
When DDLDefineBitmapExtent is enabled (n = 1), a table created by a DDL CREATE TABLE statement defines a bitmap extent index. The index improves the performance of COUNT(*), a function that returns the number of rows in the table.
Changing This Parameter
You can also change DDLDefineBitmapExtent with the Config.SQL class (as described in the class reference) or by editing the CPF in a text editor (as described in the Editing the Active CPF section of the “Introduction to the Configuration Parameter File” chapter in this book).