FORCE LOGGING Mode in Oracle:

 Force = even if someone says nologging, then we will log the *normal* redo information

=In Force logging mode Oracle database must write the redo records even when NOLOGGING is used with DDL Statements.

=It will force the write of REDO records even when no-logging is specified.

=If we write the NOLOGGING option with DDLs command then our database will not generate redo for that DDLs but in case of Dataguard or media recovery has negative impact of it. So before implement Dataguard or standby server we need to enable the FORCE LOGGING mode of the Oracle Database.So every changes should be recorded and updated in standby server while syncing.

• Force Logging is enable at tablespace and database level.
• Force logging option is by default there for undo tablespace.
• Force logging is not applicable for TEMP tablespace.

Suplemental = we log *more* than the normal redo information into the redo logs so that GG has more to work with.

NOLOGGING can be used to minimize the amount of redo generated by Oracle. Only the following operations can make use of nologging:

SQL*Loader in direct mode

INSERT /*+APPEND*/ ...

CTAS

ALTER TABLE statements (move/add/split/merge partitions)

CREATE INDEX

ALTER INDEX statements (move/add/split/merge partitions)

starting with 18c you have 2 more possibilities 

STANDBY NOLOGGING FOR LOAD PERFORMANCE

STANDBY NOLOGGING FOR DATA AVAILABILITY