Alter system 命令汇总

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Alter system archive log [start|stop|all|...]

alter system archive log all;
alter system archive log next;
alter system archive log sequence 104;
alter system archive log current;
alter system archive log current noswitch;

The following command can be used to stoparch.

alter system archive log stop

Similarly, arch is started with

alter system archive log start

However, changing the archiver this way doesn't last when the database is restarted. When the database is started, it consultslog_archive_startin the initialization file to determine ifarchis started.

Alter system archive log all

This command is used tomanually archive redo logs.

alter system disconnect session

alter system kill session

alter system kill session 'session-id,session-serial'

This command kills asession. Thesession-idandsession-serialparameters are found in thev$sessionview (columnssidandserial#.

alter system checkpoint

Performs acheckpoint

alter system checkpoint

alter system dump datafile

This command can be used in order todump one ore more blocksof adatafile. The following command dumps blocks 50 through 55 of file 5. Which file 5 is can be found out withv$datafile

alter system dump datafile 5 block min 50 block max 55;

Note:trace filesare only readable by the Oracle account. If you want to change this, set the undocumented initialization parameter_trace_files_publicto true. Doing so will, however, cause abig security risk.

alter system flush buffer_cache

alter system flush buffer_cache;

This command is not available prior to10g. It flushes thebuffer cachein theSGA.

9i had an undocumented command to flush the buffer cache:

alter sessionset events = 'immediate trace name flush_cache';

alter system flush shared_pool

alter system flush shared_pool;

This command flushed theshared pool.

alter system quiesce restricted

alter system suspend|resume

alter system switch logfile

Causes aredo log switch.

alter system switch logfile;

If the database is inarchive log mode, but theARCHprocess hasn't been startedm, the command might hang, because it waits for the archiving of the 'next'online redo log.

alter system register

Forces theregistrationof database information with thelistener.

alter system register

Alter system set timed_statistics

Setting timed_statistics=true might be usefule when usingtk prof.

Alter system set sql_trace

Setting sql_trace=true is a prerequisite when usingtk prof.

Alter system set .... deferred

Alter system can be used to changeinitialization parameterson system level. However, some parameters, when changed with alter system don't affect sessions that are already opened at the time when the statement is executet; it only affects sessions started later. These parameters must be changed withalter system set DEFERRED, otherwise aORA-02096: specified initialization parameter is not modifiable with this option error is returned.

These parameters can be identified as they have a DEFERRED in theisses_modifiablecolumn ofv$parameter.

Alter system reset

Resetsa parameter.

alter system reset some_param scope=both sid='*';

scope

scope=memory

Changes the parameter's value for the running instance only. As soon as the instance is stopped and started, this change will be lost.

scope=spfile

Alters aninitialization parameterin thespfile

scope=both

Alters aninitialization parameterin thespfileas well as in the running instance.