Logging and cascading deletes

Logging must be turned on in your database for cascading deletes to work because, when you specify a cascading delete, the delete is first performed on the primary key of the parent table. If the system fails after the rows of the primary key of the parent table are performed but before the rows of the foreign key of the child table are deleted, referential integrity is violated. If logging is turned off, even temporarily, deletes do not cascade. After logging is turned back on, however, deletes can cascade again.

HCL Informix® allows you to turn on logging with the WITH LOG clause in the CREATE DATABASE statement.