Two database users, Jack and Bill, are accessing the SupportCenter STAFF table of the SupportCenter DB database. When Jack modifies a value in the table, the new value is invisible to Bill. Which is the modified value invisible to Bill?（）

多项选择题YouworkasadatabaseadministratorforSupportcenter.cn.YouhavesettheretentionperiodforAutomaticRepository（AWR）statisticstofourdaysandcollectionintervalto15minutes.YouwanttoviewthestatisticscollectedandstoredinAWRsnapshot.WhichtwomethodswouldyouusetoviewtheAWRstatistics？（）

A.use enterprise manager
B.use DBMS_SQL package
C.use DBMS_AWR package
D.use PRVT_WORKLOAD package
E.query the AWR snapshot repository objects
F.use DBMS_WORKLOAD_REPOSITORY package

单项选择题YouworkasadatabaseadministratorforSupportcenter.cn.Inaproductionenvironment，userscomplainabouttheslowresponsetimewhenaccessingthedatabase.YouhavenotoptimizedthememoryusageoftheOracleinstanceandyoususpecttheproblemtobewiththememory.Towhichtypeofobjectwouldyourefertodeterminethecauseoftheslowresponse？（）

A.The trace file
B.The fixed views
C.The data dictionary views
D.The operating system log fields
E.The dynamic performance views.

单项选择题YouworkasadatabaseadministratorforSupportcenter.cn.Thedatabaseisopen.Amediafailurehasoccurred，resultinginlossofallthecontrolfilesinyourdatabase.Whichstatementregardingthedatabaseinstanceistrueinthisscenario？（）

A.The instance would hang.
B.The instance needs to be shut down.
C.The instance would be in the open state.
D.The instance would abort in such cases.
E.The instance would be in the open and invalid state.
F.The instance would in the open state， but all the background processes will be restarted.

多项选择题Youareworkingonatestdatabasewhereinstancerecoverytakesaconsiderableamountoftime.Howcanreducetherecoverytime？（）

A.By multiplexing the control files
B.By multiplexing the redo log files
C.By decreasing the size of redo log files
D.By configuring mean time to recover （MTTR） to a lower value
E.By setting the UNDO_RETENTION parameter to a higher value

单项选择题You work as a database administrator for Supportcenter.cn. Users in the Supportcenter.cn PROD database complain about the slow response of transactions. While investigating the reason you find that the transactions are waiting for the undo segments to be available， and undo retention has been set to zero.  What would you do to overcome this problem？（）

A.Increase the undo return
B.Create more undo segments
C.Create another undotablespace
D.Increase the size of the undo tablespace