Oracle has several logs

Oracle has 4 types of logs, namely: 1. Redo log, which is used to record all change operations in the database, including inserts, updates, and deletions; 2. Archive log, which is used to retain data in the database. Historical change record; 3. Control file log, which records the structure and status information of the database. The control file log records changes to the control file; 4. Data dictionary log, which is a key component used to store and manage database object information. , including definition information such as tables, columns, indexes, and views of the database.

#The operating environment of this article: Windows 10 system, Oracle version 19c, dell g3 computer.

Oracle is a commonly used relational database management system. It has a variety of log functions for recording the operating status and operation process of the database. In the Oracle database, there are mainly the following types of logs:

1. Redo Log:

The redo log is the most common type of log in the Oracle database. One of the important logs. It is used to record all change operations in the database, including inserts, updates, and deletes. By recording these change operations in the redo log, Oracle can ensure that the database can be restored to the most recently committed state in the event of a failure or crash.

The redo log adopts a circular writing method. When the log file is full, it will be switched to another log file to continue writing. At the same time, Oracle also supports log file archiving, which means backing up full log files to archive logs to prevent data loss.

2. Archived Redo Log:

Archived log is a backup form of redo log, used to retain historical change records in the database. When the archive mode is enabled on the database, the full redo log will be backed up to the archive log and named as a separate file.

The main function of archive logs is to provide data integrity and recovery. Through archive logs, the database can be restored from one point in time to another to meet the needs of data recovery, data auditing and replication.

3. Control File Log:

The control file is a key component of the Oracle database, which records the structure and status information of the database. , including the location and status of data files, redo logs, archive logs, etc.

The control file log records changes to the control file, such as creating databases, adding data files, and redo logs. By controlling the file log, Oracle can ensure the consistency and integrity of the database and correctly read and load other components when the database is started.

4. Data Dictionary Log:

The data dictionary is a key component in Oracle database used to store and manage database object information. It contains Definition information such as tables, columns, indexes, and views of the database.

The data dictionary log records changes to the data dictionary, such as creating and modifying table structures, adding indexes, and deleting views. Through data dictionary logs, Oracle can ensure that operations on database objects are traceable and recoverable.

Summary

Oracle database has multiple types of log functions for recording the operating status and operation process of the database. Through these logs, Oracle can ensure the integrity, consistency and recoverability of data, and improve the reliability and operating efficiency of the system. In the process of database management and failure recovery, it is very important to understand and correctly use these logs

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