单选题Why does performance degrade when many UPDATE， INSERT， or DELETE statements are issued on a tablethat has an associated Bitmap index（）A The DML operations re-create the Bitmap index blocks.B The Bitmap index is rebuilt automatically after a DML operati

题目
单选题
Why does performance degrade when many UPDATE， INSERT， or DELETE statements are issued on a tablethat has an associated Bitmap index（）
A

The DML operations re-create the Bitmap index blocks.

B

The Bitmap index is rebuilt automatically after a DML operation.

C

The smallest amount of a bitmap that can be locked is a bitmap segment.

D

Additional time is taken to remove NULL values from the Bitmap index after a DML operation.

相似考题

1.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.

2.While designing your database， you have created the EMPLOYEES table as an index-organized table （IOT）. You want to create a bitmap index on the JOB_ID column to make queries faster. Which task must have been completed so that you are able to create the bitmap index？（） 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.

3. Examine the following output： SQL> SELECT index_name，status FROM dba_indexes WHERE status=’UNUSABLE’； INDEX_NAME STATUS------------------------------ ----------- EIND UNUSABLE Which two statements about the above index are true（）A、It is ignored by the query optimizer.B、It is not used while the index is being rebuilt.C、The index cannot be rebuilt， and has to be re-created.D、The index is automatically rebuilt when used the next time

4.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.

更多“单选题Why does performance degrade when many UPDATE， INSERT， or DELETE statements are issued on a tablethat has an associated Bitmap index（）A The DML operations re-create the Bitmap index blocks.B The Bitmap index is rebuilt automatically after a DML operati”相关问题

  • 第1题：

    Which two statements are true regarding B-tree indexs（）

    • A、The leaf blocks in the index are doubly linked.
    • B、The leaf node stores a bitmap for each key value.
    • C、The rows with NULL value in key columns also have entries in the index.
    • D、The deletion of a row from the table causes a logical deletion in index leaf block and the space becomesavailable for the new leaf entry

    正确答案:A,D

  • 第2题：

    Which two statements are true about a bitmap index？ （）

    • A、It is recommended for the columns that have unique values.
    • B、It can be converted to a B-tree index by using the ALTER INDEX command.
    • C、It has a bitmap segment for each distinct value in the key column， containing a string of bits in which each bit represents the presence or absence of a key column value.
    • D、Updating the key column locks the whole bitmap segment that contains the bit for the key value to be updated.

    正确答案:C,D

  • 第3题：

    While designing your database， you have created the EMPLOYEEStable as an index-organized （IOT）. You want to create a bitmap index on the JOD_IDcolumn to make queries faster. Which task must have been completed so that you are able to create the bitmap index？（）

    • 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.

    正确答案:B

  • 第4题：

    Which two statements are correct regarding the Oracle Flashback Drop feature？ （）

    • A、 Recycle bin exists for the tables only in non-SYSTEM， locally managed tablespaces.
    • B、 You can flash back a dropped table provided row movement has been enabled on the table.
    • C、 If you drop an index before dropping its associated table， then the recovery of the index is not supported when you flash back the dropped table.
    • D、 When you execute the DROP TABLESPACE？ INCLUDING CONTENTS command， the objects in the tablespace are places in the recycle bin.
    • E、 When a dropped table is moved to the recycle bin， only the table is renamed to a system-generated name； its associated objects and constraints are not renamed.
    • F、 If you drop a table that is protected by the recycle bin， then associated bitmap-joined indexes and materialized view logs are also stored in the recycle bin.

    正确答案:A,C

  • 第5题：

    You lost the index tablespace in your database. You are not able to use tablespace point-in-time recovery on the index tablespace. What could be the reason for this？（）

    • A、 The index tablespace contains bitmap indexes.
    • B、 The index tablespace contains more than one data file.
    • C、 The index tablespace supports only complete recovery.
    • D、 The index tablespace is not a dictionary-managed tablespace.
    • E、 There is a dependency relationship between a table and its indexes.

    正确答案:E

  • 第6题：

    Why does performance degrade when many UPDATE， INSERT， or DELETE statements are issued on a tablethat has an associated Bitmap index（）

    • A、The DML operations re-create the Bitmap index blocks.
    • B、The Bitmap index is rebuilt automatically after a DML operation.
    • C、The smallest amount of a bitmap that can be locked is a bitmap segment.
    • D、Additional time is taken to remove NULL values from the Bitmap index after a DML operation.

    正确答案:C

  • 第7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.

    正确答案:A,E

  • 第8题：

    单选题
    Why does performance degrade when many UPDATE， INSERT， or DELETE statements are issued on a tablethat has an associated Bitmap index（）
    A

    The DML operations re-create the Bitmap index blocks.

    B

    The Bitmap index is rebuilt automatically after a DML operation.

    C

    The smallest amount of a bitmap that can be locked is a bitmap segment.

    D

    Additional time is taken to remove NULL values from the Bitmap index after a DML operation.


    正确答案： C
    解析： 暂无解析

  • 第9题：

    多选题
    Which two statements are true about a bitmap index？ （）
    A

    It is recommended for the columns that have unique values.

    B

    It can be converted to a B-tree index by using the ALTER INDEX command.

    C

    It has a bitmap segment for each distinct value in the key column， containing a string of bits in which each bit represents the presence or absence of a key column value.

    D

    Updating the key column locks the whole bitmap segment that contains the bit for the key value to be updated.


    正确答案： D,A
    解析： 暂无解析

  • 第10题：

    单选题
    The EMPLOYEES table has six indexes and DML operations are slow. Which command begins monitoring the EMPLOYEE_IDX_FK index to determine whether it has been used by an execution plan？（）
    A

    ALTER TABLE employees monitor index employee_idx_fk; 

    B

    ALTER INDEX employee_idx_fk monitoring on; 

    C

    ALTER TABLE employees monitor all indexes; 

    D

    ALTER INDEX employee_idx_fk monitoring usage; 


    正确答案： C
    解析： 暂无解析

  • 第11题：

    单选题
    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： E
    解析： 暂无解析

  • 第12题：

    单选题
    While designing your database， you have created the EMPLOYEEStable as an index-organized （IOT）. You want to create a bitmap index on the JOD_IDcolumn to make queries faster. Which task must have been completed so that you are able to create the bitmap index？（）
    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.


    正确答案： A
    解析： 暂无解析

  • 第13题：

    Online index rebuild functionality has been extended to include which four index structures？（）

    • A、Bitmap indexes.
    • B、Reverse key indexes.
    • C、Function-based indexes.
    • D、Key-compressed indexes on regular tables.
    • E、Key-compressed indexes on IOT （including secondary indexes）

    正确答案:B,C,D,E

  • 第14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15题：

    The EMPLOYEES table has six indexes and DML operations are slow. Which command begins monitoring the EMPLOYEE_IDX_FK index to determine whether it has been used by an execution plan？（）

    • A、ALTER TABLE employees monitor index employee_idx_fk; 
    • B、ALTER INDEX employee_idx_fk monitoring on; 
    • C、ALTER TABLE employees monitor all indexes; 
    • D、ALTER INDEX employee_idx_fk monitoring usage; 

    正确答案:D

  • 第16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17题：

    Which two statements are true regarding B-tree index（）

    • A、The leaf blocks in the index are doubly linked.
    • B、The leaf node stores a bitmap for each key value.
    • C、The rows with NULL value in key columns also have entries in the index.
    • D、The deletion of a row from the table causes a logical deletion in index leaf block and the space becomes available for the new leaf entry.

    正确答案:A,D

  • 第18题：

    A bitmap join index is defined as（）.

    • A、An index used to join two bitmap indexes on a table.
    • B、A bitmap index created for the join of two or more tables.
    • C、A bitmap index created on the join of two or more indexes.
    • D、A bitmap index created on the join of two or more indexed-organized tables.

    正确答案:B

  • 第19题：

    单选题
    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
    解析： 暂无解析

  • 第20题：

    多选题
    Examine the following output： SQL> SELECT index_name，status FROM dba_indexes WHERE status=’UNUSABLE’； INDEX_NAME STATUS------------------------------ ----------- EIND UNUSABLE Which two statements about the above index are true（）
    A

    It is ignored by the query optimizer.

    B

    It is not used while the index is being rebuilt.

    C

    The index cannot be rebuilt， and has to be re-created.

    D

    The index is automatically rebuilt when used the next time


    正确答案： B,C
    解析： 暂无解析

  • 第21题：

    多选题
    Which two statements are true regarding B-tree index（）
    A

    The leaf blocks in the index are doubly linked.

    B

    The leaf node stores a bitmap for each key value.

    C

    The rows with NULL value in key columns also have entries in the index.

    D

    The deletion of a row from the table causes a logical deletion in index leaf block and the space becomes available for the new leaf entry.


    正确答案： B,D
    解析： 暂无解析

  • 第22题：

    单选题
    A bitmap join index is defined as（）.
    A

    An index used to join two bitmap indexes on a table.

    B

    A bitmap index created for the join of two or more tables.

    C

    A bitmap index created on the join of two or more indexes.

    D

    A bitmap index created on the join of two or more indexed-organized tables.


    正确答案： A
    解析： 暂无解析

  • 第23题：

    单选题
    While designing your database， you have created the EMPLOYEES table as an index-organized table （IOT）. You want to create a bitmap index on the JOB_ID column to make queries faster. Which task must have been completed so that you are able to create the bitmap index？（）
    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.


    正确答案： D
    解析： 暂无解析

  • 第24题：

    多选题
    Which two statements are true regarding B-tree indexs（）
    A

    The leaf blocks in the index are doubly linked.

    B

    The leaf node stores a bitmap for each key value.

    C

    The rows with NULL value in key columns also have entries in the index.

    D

    The deletion of a row from the table causes a logical deletion in index leaf block and the space becomesavailable for the new leaf entry


    正确答案： C,B
    解析： 暂无解析

相关内容