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Which object may be used during query optimization to improv

题目
单选题
Which object may be used during query optimization to improve the performance for a subset of SELECT queries?（）
A

MQT

B

Trigger

C

Read Only Cursor

D

Stored Procedure

参考答案和解析
正确答案： D
解析： 暂无解析
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第1题：

Which statement is TRUE concerning buoyant work vests aboard tankers ________．

A.They may be worn while working on deck but not while working over the side

B.They must be used only under supervision of a designated ship's officer

C.They will be accepted for up to 10% of the required life preservers

D.They may be worn during drills


正确答案：B

第2题：

Which of the following statements best describes Flashback Versions Query？（）  

  • A、 Flashback Versions Query is used to make changes to multiple versions of data that existed between two points in time.
  • B、 Flashback Versions Query is used to view all version changes on rows that existed between the time  the query was executed and a point in time in the past.
  • C、 Flashback Versions Query is used to view version changes and the SQL to undo those changes on rows that existed between two points in time.
  • D、 Flashback Versions Query is used to view all version changes on rows that existed between two  points in time.

正确答案:D

第3题：

View the Exhibit for some of the parameter settings. You start a session and issue the following command:SQL>CREATE INDEX emp_ename ON emp(ename) TABLESPACE users INVISIBLE;What is the outcome of the above command?（）

A. The index is not used by the optimizer but is maintained during DML operations.

B. The index is not used by the optimizer and is not maintained during DML operations.

C. The index is used by the optimizer only if a hint is specified in the query statement and is maintained during DML operations.

D. The index is used by the optimizer only if a hint is specified in the query statement but is not maintained during DML operations.


参考答案：A

第4题：

Examine the parameter for your database instance: You generated the execution plan for the following query in the plan table and noticed that the nested loop join was done. After actual execution of the query, you notice that the hash join was done in the execution plan: Identify the reason why the optimizer chose different execution plans.（）

  • A、The optimizer used a dynamic plan for the query.
  • B、The optimizer chose different plans because automatic dynamic sampling was enabled.
  • C、The optimizer used re-optimization cardinality feedback for the query.
  • D、The optimizer chose different plan because extended statistics were created for the columns used.

正确答案:B

第5题：

Which command can be used to display information from the PvDv object class in the ODM？（）  

  • A、odmlist
  • B、odmshow
  • C、lsdev -P
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正确答案:C

第6题：

Which statements concerning the value of a member variable are true， when no explicit assignments have been made？（）  

  • A、The value of an int is undetermined.
  • B、The value of all numeric types is zero.
  • C、The compiler may issue an error if the variable is used before it is initialized.
  • D、The value of a String variable is "" （empty string）.
  • E、The value of all object variables is null.

正确答案:B,E

第7题：

Which of the following statements is true regarding the VERSIONS BETWEEN clause？（）  

  • A、 The VERSIONS BETWEEN clause may be used in DML statements.
  • B、 The VERSIONS BETWEEN clause may be used in DDL statements.
  • C、 The VERSIONS BETWEEN clause may not be used to query past DDL changes to tables.
  • D、 The VERSIONS BETWEEN clause may not be used to query past DML statements to tables.

正确答案:C

第8题：

A query is used to search through the database to locate a particular record or records, which conform. to specified (75) .

A．criteria

B．standards

C．methods

D．conditions


正确答案：A

第9题：

Which statement is true about the database and database-user used during installation of IMS Server？（）

  • A、A preexisting database user may be used but a new database has to be created during installation.
  • B、A preexisting database may be used but a new database user has to be created during installation.
  • C、A preexisting database and user may be used or a new database and user are created during installation.
  • D、A preexisting database and user cannot be used； a new database and user are created during  installation.

正确答案:C

第10题：

Which two statements are true about WHERE and HAVING clauses? （）

  • A、A WHERE clause can be used to restrict both rows and groups.
  • B、A WHERE clause can be used to restrict rows only.
  • C、A HAVING clause can be used to restrict both rows and groups.
  • D、A HAVING clause can be used to restrict groups only.
  • E、A WHERE clause CANNOT be used in a query if the query uses a HAVING clause.
  • F、A HAVING clause CANNOT be used in subqueries.

正确答案:B,D

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