An explanation of Oracle's logging mode

--Logging mode (LOGGING, FORCE LOGGING, nologging)

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First, logging mode (LOGGING, FORCE LOGGING, nologging)

1. Meaning of the three

LOGGING: Log information is logged to the online redo log file when a database object is created. Logging is actually a property of an object that is used to indicate that when an object is created

Whether to record redo logs, including whether to log redo logs when doing DML. Using nologging is not recommended on the general table, and when creating indexes or doing a lot of data import, you can use the

Nologging.

FORCE LOGGING: In short, force logging, which generates log information for all operations in the database and writes that information to the online redo log file.

Nologging: Just as opposed to LOGGING, FORCE LOGGING, log information to the online log file as much as possible.

FORCE logging can be set at the database level, at the table space level, and logging and nologging can be set at the data object level.

The force logging mode is required when using data GUARD. Note: FORCE LOGGING is not more than the general LOGGING log, the database in FORCE LOGGING

State, the nologging option will not work because Nologging will destroy Dataguard recoverability. FORCE logging forces the database to log in any state.

2. Relationship with archive mode and non-archive mode

The logging mode is not the same as the archive mode, which refers to whether the log produced by the system is archived or not archived.

In archive mode, log logs to log files and archive them. In non-archive mode, logs are also logged to log files, except that they are not archived and are easily lost.

Log mode of logging can be logged, enforced, or less logged, whether or not archived or not.

The LOGGING or force LOGGING in archive mode supports media recovery, while nologging mode does not support media recovery.

The log generated by the nologging mode operation is much smaller than the log generated by the logging mode, that is, the nologging mode minimizes logging.

3. Priority level:

When the database uses force LOGGING, it has the highest priority, followed by the Force LOGGING at the table space level. That is, when an object specifies Nologging, and the table null

or the database-level log mode is Force LOGGING, this option does not work until the Force LOGGING in the tablespace or database level is lifted.

It is generally recommended that you set the entire database to force LOGGING or set force LOGGING based on the table space level, without recommending both to force LOGGING.

When a database or table space uses a non-forced log mode, the journaling priority is from low to High: database, tablespace, data object

Use of the second and third persons

1.LOGGING mode

This is the default mode for logging, which does not change the default logging mode at the table space and object level, regardless of whether the database is in archive mode.

The log is not logged to the online redo log file for temporary table spaces.

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