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.
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;
