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This article mainly explains "what is the importance of various documents of Oracle". The content of the explanation in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "what is the importance of various documents of Oracle"?

1. Control file

The control file stores the name and status information of the database, the physical structure of the database, the information of the database backup set, as well as the information of the database SCN, CKPT, archive log and so on.

(1) query the current control file

SQL > select name from v$controlfile

NAME

/ u01/app/oracle/oradata/orcl/control01.ctl

/ u01/app/oracle/fast_recovery_area/orcl/control02.ctl

The above two control files are exactly the same and play a redundant role. It is recommended that you put the two control files in two different directories, preferably on two different disks.

two。 Data file

The data file stores the data in the database.

Data files are divided into two categories, one is the ordinary data files we store, and the other is temporary data files.

(1) query data files

SQL > select file#,name from v$datafile

FILE# NAME

--

1/ u01/app/oracle/oradata/orcl/system01.dbf

2 / u01/app/oracle/oradata/orcl/sysaux01.dbf

3 / u01/app/oracle/oradata/orcl/undotbs01.dbf

4 / u01/app/oracle/oradata/orcl/users01.dbf

(2) View temporary files

SQL > select file#,name from v$tempfile

FILE# NAME

--

1/ u01/app/oracle/oradata/orcl/temp01.dbf

3. Redo log file

The log file stores the change information of all the data in the database.

(1) View log files

SQL > select member from v$logfile

MEMBER

/ u01/app/oracle/oradata/orcl/redo03.log

/ u01/app/oracle/oradata/orcl/redo02.log

/ u01/app/oracle/oradata/orcl/redo01.log

For the database, control files, data files and log files are online files. No matter which of the three files has an error, the database will report an error. These three types of files are usually placed on storage.

4. Parameter file

Some parameters of the database are stored in the parameter file. During the database startup process, you need to read the information from the parameter file before you can start the database to the nomount state.

(1) query the location of the parameter file

SQL > show parameter spfile

NAME TYPE VALUE

Spfile string / u01/app/oracle/product/11.2.0

/ db_1/dbs/spfileorcl.ora

5. Backup file

Backup files are used for backup recovery and are offline. For backup files, the main ones are data files, control files, parameter files and archive log files. Among them, data files and archive log files must be backed up every time, but parameter files and control files do not have to be backed up every time.

Backup files must not be put on storage! It is recommended that you put the backup files on the tape library.

6. Archive log file

Archive log files are offline files, which are a kind of protective collection of log files, and are particularly important files in database files.

(1) View archived file information

SQL > select * from v$archived_log

This result reflects that when Oracle was archiving, the files were archived to this location. If Oracle is looking for an archive, it will look for an archive under the same name of this path. If you can't find it, you'll make a mistake.

Never put archived log files on storage!

7. Password file

When logging into the database remotely, a password file is required. It doesn't matter if the password file is lost, it can be generated again.

8. Alert log

All major Oracle actions and error messages will appear in this log.

The default path for Alter logs is / u01/app/oracle/diag/rdbms/orcl/orcl/trace.

This path can be changed in the parameter file.

Thank you for your reading, the above is the content of "what is the importance of various documents of Oracle". After the study of this article, I believe you have a deeper understanding of the importance of various documents of Oracle, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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