You are attempting to clear an unarchived redo log file. In order to manually enact a log switch, which of the following statements is appropriate?（）

单项选择题YouareanalyzingthecomponentsoftheredologmechanismsinyourOracledatabase.WhichofthefollowingpurposesdoestheCKPTprocessserve?（）

A.Writes buffers to disk 
B.Writes current redo log number to datafile headers 
C.Writes redo log information to disk 
D.Reads information into memory for users

单项选择题TheDBAisdefiningroleforusers.Whichofthefollowingisnotanacceptablemethodfordefiningadefaultrole?（）

A.ALTER USER DEFAULT ROLE ALL
B.ALTER USER DEFAULT ROLE ALL EXCEPT ROLE_1
C.ALTER USER DEFAULT ROLE NONE
D.ALTER USER DEFAULT ROLE NONE EXCEPT ROLE_1

单项选择题YouaredefiningareasonyourOracledatabase.Whichofthefollowingprofileareascanbeusedtocontroltheresourceusagefortheotherfour?（）

A.LOGICAL_READS_PER_SESSION 
B.CONNECT_TIME 
C.COMPOSITE_LIMIT 
D.CPU_PER_SESSION 
E.PRIVATE_SGA

单项选择题Inasituationwherenomultiplexingofredologstakesplace,whathappenswhenOraclecannotreaddatafromtheonlineredologgroupforarchiving?（）

A.Nothing happens
B.Oracle will automatically switch redo logs when detected 
C.Oracle eventually won't allow new records to be added to the database 
D.The instance crashes

单项选择题YouareanalyzinghowOracleprocessesuserstatements.SQLandPL SQLparseinformationisstoredinwhichofthefollowingdatabasememoryareas?（）

A.Library cache 
B.Row cache
C.Dictionary cache 
D.Large area 
E.Buffer cache