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ALTER SYSTEM

ALTER SYSTEM#

Syntax#

alter_system ::=#

alter_system

alter_system_set_clause ::=#

alter_session_set_clause_image247

Description#

The ALTER SYSTEM statement is used to change Altibase system properties. Only the SYS user or a user to whom the ALTER SYSTEM privilege has been granted can access the complete functionality of the ALTER SYSTEM statement.

CHECKPOINT#

This is used to execute checkpointing.

MEMORY COMPACT#

This is used to perform memory compaction. It is only useful on the IBM AIX platform.

START/STOP FLUSHER integer#

This is used to start up or shut down the flusher. The flusher identifier of the integer can be viewed by querying the V$FLUSHER performance view.

ARCHIVE LOG START/STOP#

Executing ALTER SYSTEM ARCHIVE LOG START starts the Archivelog thread, whereas ALTER SYSTEM ARCHIVE LOG STOP stops the thread. This statement can be executed only when the system is running in Archivelog mode. To determine whether the system is running in Archivelog mode, query the V$LOG or V$ARCHIVE performance view.

For more detailed information about Archivelog mode, please refer to Chapter 10: Backup and Recovery in the Administrator's Manual.

SWITCH LOGFILE#

This statement forcibly archives log files. Even if the current log file is not full, this command instructs the database to close it and resume logging in the next log file.

Only the sysdba can execute this statement.

SET alter_system_set_clause#

This statement is used to change the values of database properties. For more information about these properties, please refer to the General Reference.

FLUSH BUFFER_POOL#

This statement flushes all pages that are in the buffer to disk, thereby emptying the buffer.

Only the sysdba can execute this statement. It should only be executed after careful consideration. Because execution of this statement deletes all of the pages in the buffer, "buffer miss", that is, failure to find records that are being sought in the buffer, can occur upon subsequent query execution.

COMPACT SQL_PLAN_CACHE#

This removes the execution plan which is not being used in the SQL plan cache.

RESET SQL_PLAN_CACHE#

This removes the execution plan which is not being used in the SQL plan cache and initializes statistical information related to the plan cache.

START | STOP | RELOAD AUDIT#

This statement starts/stops auditing or reapplies auditing conditions.

RELOAD ACCESS LIST#

The RELOAD ACCESS LIST statement is used to update a list which permits or blocks the access of IP packet. This statement can be executed only in the administrator mode. The access list is comprised with the configured files in the ACCESS_LIST_FILE property. Refer to the ACCESS_LIST property for in-depth information.

Examples#

<Query> Stop flusher 1.

iSQL> ALTER SYSTEM STOP FLUSHER 1;

<Query> Start the Archivelog thread in archive mode.

iSQL> ALTER SYSTEM ARCHIVE LOG START;