Oracle Flashback: Data Recovery & Query Guide

Oracle Flashback technology is a feature used for database recovery and historical data retrieval. It allows users to quickly recover specific tables or rows without the need to recover the entire database and query the database for its data state at a specific point in the past.

The steps for implementing data recovery and historical data query using Oracle Flashback technology are as follows:

1. Enable Flashback Feature: To start using the Flashback feature, it is necessary to enable it in the database. This can be done by executing the following SQL statement.

ALTER DATABASE FLASHBACK ON;

1. Using Flashback to query historical data: You can use Flashback query statements to retrieve the data status of a database at a specific point in time in the past. For example, to query the data status of a table for the past hour, you can execute the following SQL statement:

SELECT * FROM table_name AS OF TIMESTAMP (SYSTIMESTAMP - INTERVAL '1' HOUR);

1. To recover data using Flashback Table: If you need to restore the data of a table, you can use the Flashback Table feature. For example, to recover the data state of a table from the past hour, you can execute the following SQL statement:

FLASHBACK TABLE table_name TO TIMESTAMP (SYSTIMESTAMP - INTERVAL '1' HOUR);

1. To query a transaction’s data state in the past, you can use a Flashback transaction query. For example, to check a transaction’s data state from one hour ago, you can execute the following SQL statement:

SELECT * FROM table_name VERSIONS BETWEEN TIMESTAMP (SYSTIMESTAMP - INTERVAL '1' HOUR) AND SYSTIMESTAMP;

By following the above steps, you can utilize Oracle Flashback technology to achieve data recovery and historical data querying. Please be aware that using the Flashback feature requires appropriate permissions and may consume a certain amount of system resources.