Locking and Logging Implications of Cascading Deletes
During deletes, the database server places locks on all qualifying rows of the referenced and referencing tables.
HCL OneDB™ requires transaction logging for cascading deletes. If logging is turned off in a database that is not ANSI-compliant, even temporarily, deletes do not cascade, because you cannot roll back any actions. For example, if a parent row is deleted, but the system fails before the child rows are deleted, the database will have dangling child records, in violation of referential integrity. After logging is turned back on, however, subsequent deletes cascade.