Understanding Flashback Technology - OCP: Oracle Database 12c Administrator Certified Professional - page 378

'AAARAgAAFAAAABYABd';

3 rows selected.

This query shows you the three update transactions we ran earlier to modify our
employee's salary. It also provides you with a SQL statement that could be run to effec-
tively offset the transaction.
The example query selected only a few of the columns available in the view. Table 8.4
shows the complete list.

TABle 8.4 FLASHBACK_TRANSACTION_QUERY View Columns

Column Name Description

XID Transaction identifier.

START_SCN Current SCN at start of transaction.

START_TIMESTAMP Timestamp at start of transaction.

COMMIT_SCN SCN at commit of transaction. This is the SCN associated with the

transaction.

COMMIT_TIMESTAMP Timestamp at commit of transaction.

LOGON_USER User who executed the transaction.

UNDO_CHANGE# Link to the related undo information.

OPERATION DML operation performed by the transaction.

TABLE_NAME Name of the table to which the DML is being applied.

TABLE_OWNER Owner of the table to which the DML is being applied.

ROW_ID Row ID of the row modified by the DML.

UNDO_SQL SQL to undo the transaction.

If you've ever used Oracle Log Miner, the columns listed in Table 8.4 may look familiar
to you. In fact, Flashback technology offers functionality that is very similar to Log Miner
but is much simpler to use. It allows you to drill down to the transactional level to analyze
data changes. It also provides the SQL necessary to undo any transaction, provided the
necessary undo records still exist in the undo tablespace.