The garbage collectors are active components during history management.
The garbage
collectors belong to the user kernel
threads. When the database
system is started, they are initialized using permanently stored, internal
configuration information.
During history management, the history list is used to determine the history file that is to be processed by the garbage collector. In the undo log files that were determined using the history files, the system searches for delete operations for objects. If it finds a delete operation, the garbage collector deletes the object.