多项选择题

Using a bitmap structure to manage database object space has several benefits over using freelist structures. Which three are benefits of managing space using automatic-segment-space managed objects？（）

A.It readily responds to dynamic changes for concurrent access.
B.It improves performance and space utilization in a multiple-instance environment.
C.It requires fewer space related options then freelist managed structures.
D.It improves performance for SYSTEM tablespaces where a high degree of concurrency is required.

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单项选择题

When does Oracle9i flag an index as being used in the V$OBJECT_USAGE view？（）

A.During a query’s parse time only.
B.During a query’s execution time only.
C.During any kind of DML statement execution.
D.During the execution of an INSERT statement only.

多项选择题

Which two are true regarding external tables？（）

A.External tables can be updated.
B.External tables are read-only tables.
C.Indexes can be created on external tables.
D.Indexes cannot be created on external tables.

单项选择题

Consider the following statement：
SQL> EXECUTE DBMS_STATS.GATHER_SHEMA_STATS （-
2> ownname => ‘OE’， -
3> estimate_percent => DBMS_STATS.AUTO_SAMPLE_SIZE， -
4> method opt => ‘for all columns size AUTO’）；
What is the effect of ‘for all columns size AUTO’ of the METHOD_OPT option？（）

A.The Oracle server creates a new histogram based on existing histogram definitions for all table, column, and index statistics for the OE schema.
B.The Oracle server creates a histogram based on data distribution regardless of how the application uses the column/s for all table, column, and index statistics for the OE schema.
C.The Oracle server creates a histogram based on data and application usage of the column/s for all table, column, and index statistics for the OE schema.
D.The Oracle server creates a histogram based on application usage, regardless of data distribution, for all table, column, and index statistics for the OE schema.