In one of your online transaction processing （OLTP） applications， most users frequently modify the values， including the key values， of the application tables. Some users generate application reports by using multiple application tables. 
What is the best table structure that you can use to gain optimal performance？（）

单项选择题In your test database， you have created the ORDERS table as an index­organized table （IOT）. To facilitate faster querying， you have created a mapping table and a bitmap index on the ORDER_FILLED column. You observe that the query performance degrades when users perform a large volume of transactions.  While investigating the reason， you find that the mapping table segment is fragmented， leading to poor performance. Which option would you use to defragment the mapping table without affecting the original table data？（）

A.export and import the mapping table
B.drop and re­create the mapping table
C.truncate the mapping table and reinsert the values
D.use the ALTER TABLE .. REBUILD command to defragment the mapping table

单项选择题You are designing an application for a telecom company and you have been asked to design a database table to facilitate monthly bill generation. The bill would include details of customer calls， listed in chronological order.  Which method would you follow to achieve this objective without increasing the overhead of sorting the rows？（）

A.create a hash cluster to store the data
B.create an index cluster to store the data
C.create a partitioned table to store the data
D.create a sorted hash cluster to store the data
E.create a heap table with rowid to store the data

单项选择题Inyourdatawarehousingapplication，yougeneratereportsfrequently.Thedataisstaticinthetablesbeingusedtogeneratereports.Youarecurrentlyusingjoins，resultinginalargeperformanceoverhead.Whatkindofdatabasestructurewouldyouusetoreducetheresponsetimeofthequery？（）

A.hash clusters
B.index clusters
C.partitioned tables
D.index­organized table （IOT）

单项选择题Whiledesigningyourdatabase，youhavecreatedtheEMPLOYEEStableasanindex­organizedtable（IOT）.YouwanttocreateabitmapindexontheJOB_IDcolumntomakequeriesfaster.Whichtaskmusthavebeencompletedsothatyouareabletocreatethebitmapindex？（）

A.A primary key must have been created.
B.A mapping table must have been created.
C.An overflow tablespace must have been specified.
D.The PCTTHRESHOLD option must have been specified.

单项选择题While designing the database for one of your online transaction processing （OLTP） applications， you want to achieve the following：  a） high availability of data  b） faster primary key access to the table data  c） compact storage for the table  Which type of tables would you use to achieve these objectives？（）

A.heap tables
B.object tables
C.partitioned tables
D.index­organized tables （IOTs）