Syntax options:

    JOURNAL IS ENABLED | JOURNAL IS DISABLED

    Specifies whether or not journaling is enabled.

    If journal files already exist, the JOURNAL IS ENABLED clause
    simply restarts the journaling feature.

    If no journal files exist when the ALTER DATABASE . . . JOURNAL IS
    ENABLED statement completes, an exception is raised. For example:

    SQL> ALTER DATABASE FILENAME sample
    cont> JOURNAL IS ENABLED;
    %RDMS-F-NOAIJENB, cannot enable after-image journaling without any AIJ journals

    Use the ADD JOURNAL clause to create journal files.

    The ENABLED option can be followed by a list of database journal
    options.

    All journal files remain unchanged but become inaccessible when
    you disable them. You cannot specify database journal options
    with the DISABLED option.