Your database has a table customers that contains the columns cust_name, amt_due, and
old_status.
Examine the commands executed and their output:
SQL>UPDATEcustomersSETamt_due=amt_due+amt_due*l. 1WHEREcust_name=’JAMES’;
1row updated.
SQL> ALTER TABLE customers DROP COLUMN old_status;
Table Altered
SQL> UPDATE customers SET amt_due=amt_due+amt_due*1.5 WHERE
cust_r.ame=’JAMES’;
1 row updated.
SQL> COMMIT;
SQL> SELECT versions_xid AS XID, versior.s_startscr. AS START_SCN,
versions_er.cscn AS END_SCN, versior.s_operatior. AS OPERATION’, amt_due
FROM customers VERSIONS BETWEEN SCN MINVALULEAND MAXVALUE WHERE
custname=’JAMES’;.
XIDSTART_SCNEND_SCNOPERATIONAMT_DUE
————————– ———————– ——————- ——————- ————————
07002f00cl03000017063371706337 U3300
Why is it that only one update is listed by the Flashback Version Query?
A.
Supplemental logging is not enabled for the database.
B.
The undo data that existed for versions of rows before the change to the table structure is
invalidated.
C.
The db_flash3ACK_reteni:on_target parameter is set to a lower value and the undo data
pertaining to the first transaction is flushed out.
D.
Undo retention guarantee is not enabled.
E.
Flashback Data Archive is full after the first update statement.
Wrong again! I never see anything like this almost all answers by that dude are wrong. It’s like he’s trying to sabotage!
Correct answer is B
here’s the explanation
• Flashback Query does not work through DDL operations that modify columns, or drop or truncate tables.
Limitations and Restrictions on Flashback Query
• Flashback Query is Not available after restarting the database.
• You cannot specify a subquery in the expression of the AS OF clause.
• You cannot use the VERSIONS clause in flashback queries to temporary , external tables, fixed tables, or tables that are part of a cluster.
• You cannot use the VERSIONS clause in flashback queries to views. However, you can use the VERSIONS syntax in the defining query of a view.
• You cannot specify this clause if you have specified query_name in the query_table_expression.
• Flashback Query does not undo anything. It is only a query mechanism. You can take the output from a Flashback Query and perform an undo yourself in many circumstances.
• Flashback Query does not tell you what changed. LogMiner does that.
• Flashback Query can undo changes and can be very efficient if you know the rows that need to be moved back in time. You can use it to move a full table back in time, but this is very expensive if the table is large since it involves a full table copy.
• Flashback Query does not work through DDL operations that modify columns, or drop or truncate tables.
• LogMiner is very good for getting change history, but it gives you changes in terms of deltas (insert, update, delete), not in terms of the before and after image of a row. These can be difficult to deal with in some applications.
Thanks Vonpire!
B. Thanks Vonphire!
Retrieves all the versions of the rows that exist between two points in time or two SCNs
Retrieves only committed data
Cannot be used to query external tables, temporary tables, fixed tables, or views
Can be used to create views
Cannot span DDL commands
Filters out segment shrink operations
B
B
B