Which two are valid locking levels that are used by transactions in an Oracle database？（）

单项选择题The ST_INFO master table has millions of rows that are updated very rarely. It has a STATE_CODE column that contains the value for 25 states. The table is frequently queried on the STATE_CODE column.  Which type of index would you suggest to improve the query performance？（）

A.B­tree
B.bitmap
C.reverse key
D.function based

多项选择题AconstraintinatableisdefinedwiththeINITIALLYIMMEDIATEclause.YouexecutedtheALTERTABLEcommandwiththeENABLEVALIDATEoptiontoenabletheconstraintthatwasdisabled.Whatarethetwoeffectsofthiscommand？（）

A.It fails if any existing row violates the constraint.
B.It does not validate the existing data in the table.
C.It enables the constraint to be enforced at the end of each transaction.
D.It prevents insert， update， and delete operations on the table while the constraint is in the process of being enabled.

单项选择题Your database is started by using the server parameter file （SPFILE）. You issued this command to change the value of the LOG_BUFFER initialization parameter：  ALTER SYSTEM SET LOG_BUFFER=24M SCOPE=BOTH  What would be the outcome of this command？（）

A.The command would return an error because LOG_BUFFER is a static parameter.
B.The parameter value would be changed and it would come into effect immediately.
C.You need to restart the database so that parameter changes can come into effect.
D.The command would succeed only if initialization parameter LOG_ARCHIVE_MAX_PROCESS is set to value 2.

单项选择题You are using flat files as the data source for one of your data warehousing applications. You plan to move the data from the flat file structures to an Oracle database to optimize the application performance. In your database you have clustered tables.  While migrating the data， you want to have minimal impact on the database performance and optimize the data load operation. Which method would you use to load data into Oracle database？（）

A.use the external table population
B.use the Oracle Data Pump export and import utility
C.use the conventional path data load of SQL*Loader utility
D.use the direct path data load of Oracle export and import utility

单项选择题YourdatabaseisinNOARCHIVELOGmodeandalogswitchhappensevery20minutes.OnThursdaymorning，mediafailureresultedincorruptionofadatafilebelongingtotheTOOLStablespace.BackupsaretakenoneverySunday.Whatwouldyoudointhissituation？（）

A.recover using Oracle Flashback Database technology
B.restore the data files from backup and perform a complete recovery
C.restore only the corrupted data file and perform tablespace recovery
D.restore the data files from backup and perform cancel­based recovery
E.restore the entire database from the most recent backup and start the instance and open the database