单选题The SCOTT user has an index on the ITEM_DESC column of the ITEM table. As part of the year-ending task, SCOTT updates the ITEM_DESC column for most of the rows in the ITEM table. How does this change to the table affect the index?()A An update in a lea

题目
单选题
The SCOTT user has an index on the ITEM_DESC column of the ITEM table. As part of the year-ending task, SCOTT updates the ITEM_DESC column for most of the rows in the ITEM table. How does this change to the table affect the index?()
A

An update in a leaf row takes place.

B

The index becomes invalid after the update.

C

The leaf block containing the row to be updated is marked as invalid.

D

A row in the leaf block of the index for the key value is deleted and inserted.

参考答案和解析
正确答案: D
解析: 暂无解析
如果没有搜索结果或未解决您的问题,请直接 联系老师 获取答案。
相似问题和答案

第1题:

You work in a company which uses SQL Server 2008. You are the administrator of the company database. Now you are in charge of a SQL Server 2008 instance. There is a database named named Dworks in the instance. The Dworks table has a table named BillDetails which has a clustered primary key named BillId on the BillId column. The BillDetails table has a single XML column named GoodsDetails. The XML column has an XML index and XML data are stored in this XML column. A new column named GoodsID is added to the BillDetails table. GoodsID must be included in the primary key.  So what action should you perform to achieve this goal?()  

  • A、You should drop the XML index on the table. Modify the primary key. Recreate the XML index 
  • B、You should alter the XML index and set the ALLOW_ROW_LOCKS = OFF option. Alter the primary key and set the ALLOW_ROW_LOCKS = ON option. 
  • C、You should move the XML data to a temporary table. Clear the XML data from the original table by setting the GoodsDetails column to NULL. Modify the primary key. Repopulate the ProductSpecs column. 
  • D、You should disable the XML index on the GoodsDetails column. Modify the primary key.Enable the XML index on the ProductSpecs column.

正确答案:A

第2题:

An index called ORD_CUSTNAME_IX has been created on the CUSTNAME column in the ORDERS table using the following command:   SQL>CREATE INDEX ord_custname_ix ON orders(custname);   The ORDERS table is frequently queried using the CUSTNAME column in the WHERE clause. You want to check the impact on the performance of the queries if the index is not available. You do not want the index to be dropped or rebuilt to perform this test.  Which is the most efficient method of performing this task?()

  • A、 disabling the index
  • B、 making the index invisible
  • C、 making the index unusable
  • D、 using the MONITORING USAGE clause for the index

正确答案:B

第3题:

An index called ORD_CUSTNAME_IX has been created on the CUSTNAME column in the ORDERS table using the following command:SQL>CREATE INDEX ord_custname_ix ON orders(custname);The ORDERS table is frequently queried using the CUSTNAME column in the WHERE clause.You want to check the impact on the performance of the queries if the index is not available. You do not want the index to be dropped or rebuilt to perform this test.Which is the most efficient method of performing this task?()

A. disabling the index

B. making the index invisible

C. making the index unusable

D. using the MONITORING USAGE clause for the index


参考答案:B

第4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?()

  • A、A leaf will be marked as invalid.
  • B、An update in a leaf row takes place.
  • C、The index will be updated automatically at commit.
  • D、A leaf row in the index will be deleted and inserted.
  • E、The index becomes invalid when you make any updates

正确答案:D

第5题:

You execute the following piece of code with appropriate privileges: User SCOTT has been granted theCREATE SESSION privilege and the MGR role.Which two statements are true when a session logged in as SCOTT queries the SAL column in the viewand the table?()

  • A、Data is redacted for the EMP.SAL column only if the SCOTT session does not have the MGR role set.
  • B、Data is redacted for EMP.SAL column only if the SCOTT session has the MGR role set.
  • C、Data is never redacted for the EMP_V.SAL column.
  • D、Data is redacted for the EMP_V.SAL column only if the SCOTT session has the MGR role set.
  • E、Data is redacted for the EMP_V.SAL column only if the SCOTT session does not have the MGR role set.

正确答案:A,C

第6题:

A warehouse fact table in your Oracle 12c Database is range-partitioned by month and accessed frequently with queries that span multiple partitions The table has a local prefixed, range partitioned index. Some of these queries access very few rows in some partitions and all the rows in other partitions, but these queries still perform a full scan for all accessed partitions. This commonly occurs when the range of dates begins at the end of a month or ends close to the start of a month. You want an execution plan to be generated that uses indexed access when only a few rows are accessed from a segment, while still allowing full scans for segments where many rows are returned. Which three methods could transparently help to achieve this result?()

  • A、Using a partial local Index on the warehouse fact table month column with indexing disabled to the table partitions that return most of their rows to the queries.
  • B、Using a partial local Index on the warehouse fact table month column with indexing disabled for the table partitions that return a few rows to the queries.
  • C、Using a partitioned view that does a UNION ALL query on the partitions of the warehouse fact table, which retains the existing local partitioned column.
  • D、Converting the partitioned table to a partitioned view that does a UNION ALL query on the monthly tables, which retains the existing local partitioned column
  • E、Using a partial global index on the warehouse fact table month column with indexing disabling for the table partitions that return most of their rows to the queries.
  • F、Using a partial global index on the warehouse fact table month column with indexing disabled for the table partitions that return a few rows to the queries.

正确答案:B,C,F

第7题:

As a result of performance analysis, you created an index on the prod_name column of the prod_det table, which contains about ten thousand rows. Later, you updated a product name in the table. How does this change affect the index?()

  • A、A leaf will be marked as invalid.
  • B、An update in a leaf row takes place.
  • C、The index will be updated automatically at commit.
  • D、A leaf row in the index will be deleted and inserted.
  • E、The index becomes invalid when you make any updates.

正确答案:D

第8题:

You have altered a non-unique index to be invisible to determine if queries execute within an acceptable response time without using this index.Which two are possible if table updates are performed which affect the invisible index columns?()

A. The index remains invisible.

B. The index is not updated by the DML statements on the indexed table.

C. The index automatically becomes visible in order to have it updated by DML on the table.

D. The index becomes unusable but the table is updated by the DML.

E. The index is updated by the DML on the table.


参考答案:A, E

第9题:

You need to change the definition of an existing table. The COMMERCIALS table needs its DESCRIPTION column changed to hold varying length characters up to 2000 bytes. The column can currently hold 1000 bytes per value. The table contains 20000 rows. Which statement is valid?()

  • A、ALTER TABLE commercials MODIFY (description CHAR2(2000));
  • B、ALTER TABLE commercials CHANGE (description CHAR2(2000));
  • C、ALTER TABLE commercials CHANGE (description VARCHAR2 (2000));
  • D、ALTER TABLE commercials MODIFY (description VARCHAR2 (2000));
  • E、You cannot increase the size of a column if the table has rows.

正确答案:D

第10题:

The user HR owns the EMP table. The user HR grants privileges to the user SCOTT by using this command:  SQL> GRANT SELECT,INSERT,UPDATE ON emp TO scott WITH GRANT OPTION; The user SCOTT executes this command to grant privileges to the user JIM: SQL> GRANT SELECT,INSERT,UPDATE ON hr.emp TO jim;  Now, the user HR decides to revoke privileges from JIM using this command: SQL> REVOKE SELECT,INSERT,UPDATE ON emp FROM jim; Which statement is true after HR issues the REVOKE command()

  • A、The command fails because SCOTT still has privileges.
  • B、The command succeeds and privileges are revoked from JIM.
  • C、The command fails because HR cannot revoke the privileges from JIM.
  • D、The command succeeds and only HR has the privilege to perform the SELECT, INSERT, and UPDATEoperations on the EMP table.

正确答案:C

更多相关问题