Which two are prerequisites for performing a flashback transaction?
A.
Flashback Database must be enabled.
B.
Undo retention guarantee for the database must be configured.
C.
EXECUTE privilege on the DBMS_FLASHBACK package must be granted to the user flashing
back transaction.
D.
Supplemental logging must be enabled.
E.
Recycle bin must be enabled for the database.
F.
Block change tracking must be enabled tor the database.
Explanation:
B: Specify the RETENTION GUARANTEE clause for the undo tablespace to ensure
that unexpired undo data is not discarded.
C: You must have the EXECUTE privilege on the DBMS_FLASHBACK package.
Note:
*Use Flashback Transaction to roll back a transaction and its dependent transactions while the
database remains online. This recovery operation uses undo data to create and run the
corresponding compensating transactions that return the affected data to its original state.
(Flashback Transaction is part ofDBMS_FLASHBACKpackage.)
Reference: Oracle Database Advanced Application Developer’s Guide 11g, Using Oracle
Flashback Technology
Correct answer is B & C.
Supplemental logging must be enabled for flashback transaction.
Remember, flashback transaction is based on LogMiner.
Sorry, I meant C & D.
Yes, C and D.
Configuring Your Database for Flashback Transaction
http://docs.oracle.com/cd/E11882_01/appdev.112/e41502/adfns_flashback.htm#BJFHBGGE
Undo is also needed but retention guarantee is not necessary.
i think BCD are correct, undo retention is necessary
http://docs.oracle.com/cd/E11882_01/appdev.112/e41502/adfns_flashback.htm#ADFNS609
B is WRONG. “Undo retention guarantee” is optional. But “Undo retention” is required.
The “guarantee” makes this requirement wrong.
Oracle in KB write:
C –
To allow access to the features in the DBMS_FLASHBACK package, grant the EXECUTE privilege on DBMS_FLASHBACK.
D –
1. Database must be running in archivelog mode.
SQL> alter database archivelog;
2. Supplemental logging must be turned on at the database level.
SQL> alter database add supplemental log data;
this is writen for undo configuration not for FB and is not neded!
Specify the RETENTION GUARANTEE clause for the undo tablespace to ensure that unexpired undo data is not discarded.
CD
CD and if 3 option will go with b
CD, only 2 answers are required.
To use AS OF TIMESTAMP you don’t need EXECUTE privilege on DBMS_FLASHBACK. So for me the answer is B and D
CD
CD
CD
Very nice Demo:
http://www.oracleflash.com/31/Oracle-11g-DBMS_FLASHBACK-TRANSACTION_BACKOUT.html
CD
CD
C,D are correct
C,D
just beneath, are various totally not associated web sites to ours, having said that, they are surely worth going over
here are some hyperlinks to internet sites that we link to mainly because we feel they’re really worth visiting
Wonderful story, reckoned we could combine a few unrelated information, nonetheless seriously really worth taking a search, whoa did a single master about Mid East has got a lot more problerms too
why everyone insist supplemental logging needed? Tested, is not needed
select SUPPLEMENTAL_LOG_DATA_MIN,SUPPLEMENTAL_LOG_DATA_PK,SUPPLEMENTAL_LOG_DATA_UI from v$database;
SUPPLEME SUP SUP
——– — —
NO NO NO
select LOG_MODE,FLASHBACK_ON from v$database;
LOG_MODE FLASHBACK_ON
———— ————
ARCHIVELOG NO
–archive log is on, database flashback turned off
select name,flashback_on from v$tablespace;
— all YES
create table t1 as select * from dba_objects;
select count(*) from t1;
— 91,286
select to_char(sysdate,’yyyyMONdd_hh24mi:ss’)”DT”,dbms_flashback.get_system_change_number() scn from dual;
DT SCN
————————– ————————
2017NOV14_0601:28 16,826,024
delete from t1;
commit;
select count(*) from t1;
–0
select count(*) from t1 as of timestamp to_timestamp(‘2017NOV14_0601:28′,’yyyyMONdd_hh24mi:ss’);
— 91,286
select count(*) from t1 as of scn 16826024;
— 91,286
UNDO is needed, if not will get snapshot too old. If query within GUARANTEE period, query succeed
my choice BC