多选题Which two statements are true regarding B-tree index（）AThe leaf blocks in the index are doubly linked.BThe leaf node stores a bitmap for each key value.CThe rows with NULL value in key columns also have entries in the index.DThe deletion of a row from 

题目
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.

相似考题

1.Consider the following:Which statement best describes the meaning of the value for the key_len column?()A.It shows the total size of the index rowB.It shows how many columns in the index are examinedC.It shows the number of characters indexed in the keyD.It shows how many bytes will be used from each index row

2.Which two statements are true about constraints? （）A、The UNIQUE constraint does not permit a null value for the column.B、A UNIQUE index gets created for columns with PRIMARY KEY and UNIQUE constraints.C、The PRIMARY KEY and FOREIGN KEY constraints create a UNIQUE index.D、The NOT NULL constraint ensures that null values are not permitted for the column.

3.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

4.The InnoDB engine has a feature known as clustered indexes.Which three statements are true about clustered indexes as used in InnoDB?()A.A primary key must exist for creation of a clustered indexB.A clustered index allows fulltext searching within InnoDBC.The first unique index is always used as a clustered index and not a primary keyD.A clustered index provides direct access to a page containing row dataE.If no indexes exist, a hidden clustered index is generated based on row IDsF.A primary key is used as a clustered indexG.A clustered index is a grouping of indexes from different tables into a global index for faster searching

参考答案和解析
正确答案： D,C
解析： 暂无解析
更多“多选题Which two statements are true regarding B-tree index（）AThe leaf blocks in the index are doubly linked.BThe leaf node stores a bitmap for each key value.CThe rows with NULL value in key columns also have entries in the index.DThe deletion of a row from ”相关问题

  • 第1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2题：

    What two statements are true regarding the recommendations received from the SQL Access Advisor?（）(Choose two.)

    • A、It cannot generate recommendations that support multiple workload queries.
    • B、It can recommend partitioning on tables provided that the workloads have some predicates and joins on the columns of the NUMBER or DATE type.
    • C、It can recommend partitioning only on tables that have at least 10,000 rows.
    • D、It can recommend only B-tree indexes and not bitmap or function-based indexes

    正确答案:B,C

  • 第3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4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5题：

    What two statements are true regarding the recommendations received from the SQL Access Advisor？（）

    • A、 It cannot generate recommendations that support multiple workload queries.
    • B、 It can recommend partitioning on tables provided that the workloads have some predicates and joins on the columns of the NUMBER or DATE type.
    • C、 It can recommend partitioning only on tables that have at least 10，000 rows.
    • D、 It can recommend only B-tree indexes and not bitmap or function-based indexes.

    正确答案:B,C

  • 第6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7题：

    多选题
    Which two statements regarding asymmetric key encryption are true？（）
    A

    The same key is used for encryption and decryption.

    B

    It is commonly used to create digital certificate signatures.

    C

    It uses two keys： one for encryption and a different key for decryption.

    D

    An attacker can decrypt data if the attacker captures the key used for encryption


    正确答案： D,B
    解析： 暂无解析

  • 第8题：

    单选题
    Which statement describes the effect on an index， when the indexed column for the rows is updatedin the base table（）
    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 logically deleted and a new leaf row is inserted


    正确答案： B
    解析： 暂无解析

  • 第9题：

    多选题
    The InnoDB engine has a feature known as clustered indexes. Which three statements are true about clustered indexes as used in InnoDB?（）
    A

    A primary key must exist for creation of a clustered index

    B

    A clustered index allows fulltext searching within InnoDB

    C

    The first unique index is always used as a clustered index and not a primary key

    D

    A clustered index provides direct access to a page containing row data

    E

    If no indexes exist, a hidden clustered index is generated based on row IDs

    F

    A primary key is used as a clustered index

    G

    A clustered index is a grouping of indexes from different tables into a global index for faster searching


    正确答案： D,E,F
    解析： 暂无解析

  • 第10题：

    多选题
    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： B,A
    解析： 暂无解析

  • 第11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12题：

    多选题
    Which two statements regarding symmetric key encryption are true?（） (Choose two.)
    A

    The same key is used for encryption and decryption.

    B

    It is commonly used to create digital certificate signatures.

    C

    It uses two keys: one for encryption and a different key for decryption.

    D

    An attacker can decrypt data if the attacker captures the key used for encryption.


    正确答案： D,B
    解析： 暂无解析

  • 第13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14题：

    Which statement describes the effect on an index， when the indexed column for the rows is updatedin the base table（）

    • 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 logically deleted and a new leaf row is inserted

    正确答案:D

  • 第15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.

    正确答案:D

  • 第16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17题：

    The InnoDB engine has a feature known as clustered indexes. Which three statements are true about clustered indexes as used in InnoDB?（）

    • A、A primary key must exist for creation of a clustered index
    • B、A clustered index allows fulltext searching within InnoDB
    • C、The first unique index is always used as a clustered index and not a primary key
    • D、A clustered index provides direct access to a page containing row data
    • E、If no indexes exist, a hidden clustered index is generated based on row IDs
    • F、A primary key is used as a clustered index
    • G、A clustered index is a grouping of indexes from different tables into a global index for faster searching

    正确答案:D,E,F

  • 第18题：

    多选题
    What two statements are true regarding the recommendations received from the SQL Access Advisor?（）(Choose two.)
    A

    It cannot generate recommendations that support multiple workload queries.

    B

    It can recommend partitioning on tables provided that the workloads have some predicates and joins on the columns of the NUMBER or DATE type.

    C

    It can recommend partitioning only on tables that have at least 10,000 rows.

    D

    It can recommend only B-tree indexes and not bitmap or function-based indexes


    正确答案： D,C
    解析： 暂无解析

  • 第19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20题：

    多选题
    What two statements are true regarding the recommendations received from the SQL Access Advisor？（）
    A

    It cannot generate recommendations that support multiple workload queries.

    B

    It can recommend partitioning on tables provided that the workloads have some predicates and joins on the columns of the NUMBER or DATE type.

    C

    It can recommend partitioning only on tables that have at least 10，000 rows.

    D

    It can recommend only B-tree indexes and not bitmap or function-based indexes.


    正确答案： A,D
    解析： 暂无解析

  • 第21题：

    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.


    正确答案： B
    解析： 暂无解析

  • 第22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23题：

    多选题
    Which two statements are true about constraints? （）
    A

    The UNIQUE constraint does not permit a null value for the column.

    B

    A UNIQUE index gets created for columns with PRIMARY KEY and UNIQUE constraints.

    C

    The PRIMARY KEY and FOREIGN KEY constraints create a UNIQUE index.

    D

    The NOT NULL constraint ensures that null values are not permitted for the column.


    正确答案： A,B
    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

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