Flash Back Corrections

Flashback Versions Query retrieves all committed occurrences of the rows.  However, the VERSIONS BETWEEN clause is not applicable for querying the views.

The Flashback Versions Query can be used to audit a table and retrieve information about the transactions that changed any of the rows. The Transaction ID obtained from Flashback Versions Query can be used to do transaction mining using LogMiner. Similarly, Flashback Transaction Query can be used to get additional information about the transaction.

The Flashback Versions Query returns the versions of the rows and validity range of the version, the transaction ID of the transaction that created the version, and the operation that created that version. The validity range is closed at the lower end and opened at the upper end.  This range information is stored in pseudo columns. These pseudo columns can be used in the SELECT clause to display their values or in the WHERE clause to retrieve specific versions of the rows.

All Flashback features rely on undo information to recreate a state in the past. For an undo tablespace, the tablespace retention clause can be used to control preservation of unexpired undo data. The RETENTION GUARANTEE clause of the CREATE UNDO TABLESPACE and CREATE DATABASE specifies that unexpired undo data should be retained in all undo segments in the tablespace even if the undo generating operations fail.