How Oracle records modification records

With the continuous development of business and the continuous growth of data, the query and management of data modification records have become more and more important. The Oracle database provides a convenient and fast function for recording modification records. This article will introduce how Oracle records modification records and how to query and manage these records.

Record modification records

Oracle database provides two methods to record modification records: Flashback technology and Audit technology.

Flashback technology

Flashback technology is a technology provided by Oracle database to quickly roll back the state of database objects. It can be used to roll back the state of a table or the entire database. The record modification record is a subset of Flashback technology, and Oracle provides a special function called Flashback Data Archive.

Create Flashback Data Archive

You need to create Flashback Data Archive before using Flashback Data Archive to record modification records. Flashback Data Archive can be created through the following SQL statement:

CREATE FLASHBACK ARCHIVE fda1
TABLESPACE example
QUOTA 100M
RETENTION 1 YEAR
NO DROP;

The above statement creates a Flashback Data Archive named fda1, uses the example table space, allocates 100M space, the data retention period is 1 year, and cannot be recycled immediately.

Enable Flashback Data Archive

After creating Flashback Data Archive, you need to enable Flashback Data Archive for the table or specific columns in the table. Suppose you want to enable Flashback Data Archive for the salary column in the EMPLOYEE table, you can use the following SQL statement:

ALTER TABLE employee
ADD PERIOD FOR salary
FLASHBACK ARCHIVE fda1;

The above statement adds Flashback Data Archive for the salary column in the EMPLOYEE table. Any updates made to the EMPLOYEE table will now be logged in the Flashback Data Archive.

Audit technology

Audit is another tool provided by Oracle database to record modification records. It can track and record the transactions performed by users on the database server. Audit technology is basically a must in the enterprise environment of Oracle database because it can help managers track and identify users who access a database object.

Set audit parameters

You need to set audit parameters before using Audit technology to record modification records. You can use the following SQL statement to enable auditing:

ALTER SYSTEM SET audit_trail=DB, EXTENDED SCOPE=SPFILE;

Set the audit trail of the Oracle database to DB to enable the database audit trail function. The SCOPE=SPFILE parameter indicates that the setting will be recorded in SPFILE.

Enable Audit

To enable Audit tracking, you need to configure the database. Auditing can be enabled for the sys user using the following SQL statement:

AUDIT UPDATE ANY TABLE BY ACCESS;

The above command enables auditing of access to any table modified by the sys user.

Query and manage record modification records

Once modified records are recorded, you can start querying and managing these records. Oracle provides multiple methods to query and manage record modification records.

Query Flashback Data Archive

To query historical data in Flashback Data Archive, you can use the following SQL statement:

SELECT *
FROM table_name
AS OF TIMESTAMP TO_TIMESTAMP('YYYY-MM-DD HH24:MI:SS.FF');

The timestamp can be what happened on the Flashback Data Archive server any time. For the above example, the date and time format used is YYYY-MM-DD HH24:MI:SS.FF.

Query the Audit log

To query the Audit log, you can use the following SQL statement:

SELECT *
FROM dba_audit_trail

This command will display all audit events of the queried database.

Manage record modification records

When the data modification record log file reaches the specified size, Oracle will automatically add a new log file. You can look in the log file for records of changes to data recently added to the data table. To manage these change recording log files, use the following command:

ALTER FLASHBACK ARCHIVE [archive_name] PURGE ALL

is used to delete selected Flashback Data Archive log files. After using the above command, the selected Flashback Data Archive log file will be permanently deleted and cannot be recovered.

Summary

Oracle provides a series of methods to record modification records. Flashback technology can record changes in tables or entire databases. Audit can record all transactions performed on the database server. Once modification records exist, we can use multiple methods to query and manage them. The above method can help administrators track the operations of modifiers and regularly check and record modification records to maintain the data integrity of the database.

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