DM8 archive log file manual switching

Archive log switch

Here, the database is used as a stand-alone , For example, local archiving has been enabled , Test the switching of archive log files .

Because the local archive is written to the archive log file asynchronously ,REDO The log is written to the online log file , Then, a special archiving thread is responsible for these REDO The log is written to the local archive log file . Switch functions through archiving , These can be written to the online log file , Those that have not been written to the archive log file REDO journal , Write to archive log file .

Perform the following SQL command , The archive switching function can be completed . Three sentence function system , When switching manually, you only need to select one to execute . This chapter will test from these three statements .

SQL>alter database archivelog current;SQL>alter system archive log current;SQL>alter system switch logfile;

Before the test , We use the following statement to query the archived log file information .

SQL>select t.STATUS, t.PATH, t.ARCH_LSN, t.CLSN from "V$ARCH_FILE"t;

The results are as follows , You can see the... In the database 16 Archive files are active , The description is that this file is an archive log file in use .

Mode one (alter database archivelog current)

Do some simple inserts 、 Delete or create tables and other data operations , Use the following command to switch archiving ：

SQL>alter database archivelog current;

Query again V$ARCH_FILE You can see the 16 Files have been INACTIVE state .

Wait a moment to inquire , You can see the generation of 17 Archive files , Status as ACTIVE.

Mode two (alter system archive log current)

Delete the table you just created , Or simply insert 、 to update 、 Delete table data and other database operations , Use the following command to switch archiving ：

SQL>alter system archive log current;

Query again V$ARCH_FILE You can see the 17 Files have been INACTIVE state .

Wait a moment to inquire , You can see the generation of 18 Archive files , Status as ACTIVE.

Mode three (alter system switch logfile)

Do some simple inserts 、 Delete or create tables , Then use the following command to switch archiving ：

SQL>alter system switch logfile;

Query after operation V$ARCH_FILE, You can see the 18 Files have been INACTIVE state .

Wait a moment to inquire , You can see the generation of 19 Archive files , Status as ACTIVE.