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Flashback Data Archive

The flashback data archive provided in the 11g version of Oracle database can view the status of any previous timesheet. Using flashback data archive, you can store the front image of a row indefinitely. In comparison, Oracle's other flashback technologies have time limits: for example:

(1) Flashback database flashback database: limited by the size of the flashback log

(2), Flashback select flashback query, flashback transaction, flashback table flashback table are all restricted by undo retention

(3). Flashback drop limits on the size of available tablespaces (starting with 11g, the deleted table actually performs a rename operation and is not actually deleted, which can be viewed through the Recycle Bin)

1. The implementation principle of Flashbackup Data Archive:

When Flashbackup Data Archive is enabled for a table, another table (and several other objects) is created, which can be used to store all previous versions of rows, and they can be stored forever if desired. When the DML operation is submitted for the table, a background process called flashback data archive (FBDA) will capture the necessary data and save them to the archive file. Is an archive of flashback data archive), so you can use flashback data archive to go back many years.

2. Flashback data archive data preservation restrictions and expired data processing.

The time limit can be enforced when the flashback data archive is created. FBDA can save all the data before that point in time, and the expired data will be deleted automatically. FDBA is responsible for creating objects in the archive and populating them with rows as needed. And clear the data that is out of validity.

3. New discoveries in practice

New discovery: in the actual testing process, it is found that flashback data archive can also capture add a column to a table commands in ddl.

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