History files are
used during history
management. A history file is
an internal database file, which contains the access and statistical
information about the undo log files of
transactions that
have ended.
When a database
instance is created, the initial history files are stored in the data area.
The number of history files is defined
by the database parameter
MAXUSERTASKS.
Once a transaction has ended, it writes
an entry to its history file. This entry identifies the undo log file that is
assigned to the transaction. With
each
savepoint, the
history file is saved to the data area.
The history list is used to assign the history files to the garbage collectors.