ALTER SYSTEM LOGGING Statement (System Management)

Enables or disables logging.

Syntax

ALTER SYSTEM LOGGING <on_off>

Syntax Elements

<on_off>

Specifies the logging status.

<on_off> ::= ON | OFF

ON

Enables logging.

OFF

Disables logging.

Description

While logging is disabled, no log entries persist; only the data area is written when a savepoint is reached. This behavior can cause the loss of committed transactions when the indexserver terminates in the middle of a LOAD operation. In case of a termination, truncate and insert all data again.

Note

Logging mode cannot be disabled on the primary system when system replication is used.

After enabling logging, perform a savepoint to be sure that all data persists. You must also perform a data backup; otherwise, you are unable to recover this data.

ALTER SYSTEM LOGGING waits for the end (commit/rollback) of existing active write transactions. During the execution of this command, write transactions are blocked. In the event that there is a long-running write transaction, this command can fail with a lock wait timeout error. Starting a new write transaction also can be blocked and failed with the same error.

Only use this command while performing the initial load of a database. If this statement is used at other times, then data loss can occur if the indexserver is terminated while logging is disabled. Consequently, in a running system, the logging mode should be always ON and should not be modified.

Example

Disable system logging.

ALTER SYSTEM LOGGING OFF;

Enable system logging.

ALTER SYSTEM LOGGING ON;

Related Information

ALTER TABLE Statement (Data Definition)