单项选择题
A.It degrades the run time and compiler performance.
B.It provides better run time and compiler performance.
C.It provides better optimization of the statement during parse time.
D.It forces the rule based optimizer to be used for statement optimization.
E.It provides better run time performance but slightly degraded compiler performance.
F.It provides better run time performance but slightly degraded run time performance.
单项选择题 You work as a database administrator for Certkiller .com. You find that reports are running for a long time in your data warehousing applications. You suspect a lack of indexes is the reason for the performance degradation. Which advisory component would you refer to， in order to determine the appropriate indexes？（）
单项选择题 Two database users， Jack and Bill， are accessing the Certkiller STAFF table of the Certkiller 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？（）
单项选择题 You work as a database administrator for Certkiller .com. As a result of performance analysis， you created an index on theprod_namecolumn of the Certkiller prodtable， which contains about ten thousand rows. Later， you updated a product name in the table. How does this change affect the index？（）