Log File mode in oracle

Log File mode in oracle

There are two log modes in oracle Database: Non-archive log mode and archive log mode.

In the oracle database system, to prevent the contents of log files from being overwritten during cyclic use, the oracle System

Copy and save a fully-written log file to a specified place through the file. This process is called "ARCHIVE" and saved.

The log file is called "archive log". All the modifications to the database are recorded in the archive log file.

Archive log files. The database administrator can restore the database.

Log file archiving is automatically completed by the background process ARCn. If necessary, the database administrator

You can manually archive logs. When you need to improve the efficiency of log archiving, you can start multiple archiving processes (AR ).

Cn. The maximum number of ARCn processes to be started depends on the log_archive_processes parameter. The range of this parameter is 1-10.

Through the data dictionary V $ PARAMETER, you can understand the information of this PARAMETER.

SQL> columnname format a30

SQL> columnvalue format a20

SQL> selectname, value from v $ parameter

2 where name = 'Log _ archive_max_processes ';

NAME VALUE

--------------------------------------------------

Log_archive_max_processes 4

SQL>

From the above results, we can see that the value of the log_archive_processes parameter is 4, indicating that up to 4

ARCn processes. You can use the alter system command to change the value of the log_archive_processes parameter to 10,

SQL> ALTERSYSTEM SET log_archive_max_processes = 10

2 scope = both;

The system has been changed.

The scope parameter is used in the preceding command. This parameter has three optional values: memory,

Spfile and both. Memory indicates that the parameters of the current instance are modified, and spfile indicates that the server parameters are modified.

File spfile settings; both indicates that the parameters of the currently running instance are modified, and the Server File spfile is modified.

. Query again as follows:

SQL> selectname, value from v $ parameter

2 where name = 'Log _ archive_max_processes ';

NAME VALUE

--------------------------------------------------

Log_archive_max_processes 10