Sets the SQL(BEHAVIOR) directive to SQL(BEHAVIOR=OPTIMIZED), meaning that data access is read only for everything except data access that is explicitly specified for update.
For database connections to Microsoft SQL Server, multiple active result sets (MARS) are enabled and read only cursors use SQL Server default result sets (otherwise known as firehose cursors). Be sure to use the most recent Microsoft ODBC driver for your version of SQL Server; older versions of the Microsoft ODBC for SQL Server might not provide MARS functionality.
For other databases, such as Oracle or DB2, read only cursors use block fetches of eight rows.
Updatable cursors for all databases use block fetches of eight rows. You can change the block fetch size.