Deck 9: Managing Multiuser Databases

Question 1

Explicit locks are locks that are placed automatically by the DBMS.

Answer 1

False

Question 2

Changes in the database structure usually involve only one application.

Answer 2

False

Question 3

An exclusive lock locks the item from access of any type.

Answer 3

True

Question 4

The DBA is responsible for managing changes to the database structure,but is rarely involved in the original design of the structure.

Question 5

Database administration is more important but less difficult in multiuser database systems than in single-user database systems.

Question 6

Locks placed by a command issued to the DBMS from the application program are called explicit locks.

Question 7

An exclusive lock locks the item from change but not from read access.

Question 8

One important reason for documenting changes to the database structure is for diagnosing errors.

Question 9

Locks with large granularity are easy for the DBMS to administer but frequently cause conflicts.

Question 10

A transaction is a group of alternative database actions,from which the database can choose to perform only one of them.

Question 11

Locks placed automatically by the DBMS are called implicit locks.

Question 12

Resource locking is one remedy to the lost update problem.

Question 13

The size of a lock is referred to as the lock granularity.

Question 14

A transaction is sometimes called atomic because it is performed as a unit.

Question 15

The DBA has to find a balance between the conflicting goals of maximizing availability of the database to users and protecting the database.

Question 16

Database administration tasks have to be performed for single-user,personal databases.

Question 17

A transaction is a series of actions to be taken on the database such that either all of them are performed successfully or none of them is performed at all.

Question 18

Concurrency control measures are taken to ensure that one user's work has absolutely no influence on another user's work.

Question 19

In general,the overall responsibility of the DBA is to facilitate the development and use of the database system.

Question 20

The database is most vulnerable to failure after a change to its structure.

Question 21

In two-phase locking,all locks are released during the contracting phase.

Question 22

With optimistic locking,the assumption is made that no conflict will occur.

Question 23

A dynamic cursor saves primary key values when the cursor is opened and retrieves the values for each row as the application program accesses it.

Question 24

In two-phase locking,all locks are obtained during the growing phase.

Question 25

Repeatable Read isolation is the most restrictive level of isolation.

Question 26

With pessimistic locking,the assumption is made that a conflict will occur.

Question 27

Two-phased locking is a scheme for achieving serializability of transactions.

Question 28

Transaction level consistency means that all rows impacted by any actions in a transaction are protected from change during the entire transaction.

Question 29

Nonrepeatable reads occur when a transaction rereads data it has previously read and finds modifications or deletions caused by a committed transaction.

Question 30

The goal of database security is to ensure that only authorized users can perform authorized activities at authorized times.

Question 31

The transaction boundaries are the essential information that the DBMS needs from the application programs to enforce different locking strategies.

Question 32

Requiring all application programs to lock resources in the same order is one way of preventing a deadlock condition.

Question 33

Resources are locked for a shorter amount of time with pessimistic locking because the transaction is pre-processed.

Question 34

In general,optimistic locking is the preferred technique for Internet databases.

Question 35

A static cursor processes a snapshot of the relation that was taken when the cursor was opened.

Question 36

A dirty read happens when one transaction reads a changed record that has not been committed to the database.

Question 37

Two-phased locking has a growing phase and a shrinking phase.

Question 38

A durable transaction is one for which all committed changes are permanent.

Question 39

According to ANSI SQL,the serializable isolation level will not allow phantom reads,dirty reads,and nonrepeatable reads.

Question 40

Resource locking must be carefully planned because most DBMS products cannot detect a deadlock condition.

Question 41

All commercial DBMS products use some version of "username and password" as part of their security features.

Question 42

A standby data repository is one which requires a person to generate the metadata and place it in the repository.

Question 43

A passive data repository is preferred over an active repository because it requires less human intervention.

Question 44

Reprocessing is normally the most convenient method for recovery after a system failure.

Question 45

A checkpoint is a point of synchronization between the database and the transaction log.

Question 46

Both rollforward and rollback require the use of a log of transaction results.

Question 47

Rollforward is a method of database recovery that restores the database save and all valid transactions since the save was reapplied.

Question 48

Which of the following is true about making changes to the database structure?

A)The DBA need not get input from users on the issue because it is a technical decision.
B)Formal policies and procedures for requesting a change are not used because they are too limiting.
C)Documentation of when the change was made,how it was made,and why it was made must be created.
D)Changes do not produce unexpected results because the DBA will have investigated the change thoroughly before implementing it.
E)If the database is properly designed,changes should not be necessary throughout the system's lifetime.

Question 49

The security provided by the DBMS often has to be augmented by additional security features within the application program.

Question 50

Rollforward and reprocessing are two different names for the same technique.

Question 51

An active data repository is one in which the metadata is automatically created as the system components are created.

Question 52

Copies of each database record or page after it was changed by a transaction that are saved for use in database recovery are called ghost images.

Question 53

Processing responsibilities should be documented and encoded into manual procedures.

Question 54

Which of the following is not a database administration responsibility of a DBA?

A)Managing the database structure
B)Managing data activity
C)Managing the DBMS
D)Maintaining the data repository
E)All of the above are database administration responsibilities of a DBA.

Question 55

In regard to database security,neither the DBMS nor the database applications can enforce processing responsibilities.

Question 56

Copies of each database record or page before being changed by a transaction that are saved for use in database recovery are called before images.

Question 57

The DBA should periodically analyze run-time statistics of database performance to help manage the DBMS.

Question 58

A "database save" is used to mark the end of a transaction.

Question 59

To support rollforward and rollback recovery,transactions must be written to a script before they are applied to the database.

Question 60

Processing rights may be implemented at the DBMS level.

Question 61

Which of the following is true of forward only cursors?

A)Current values for each row are retrieved when the application accesses a row.
B)All changes of any type from any source are visible.
C)Changes made by the transaction are visible only if they occur on rows ahead of the cursor.
D)Applications may scroll backward in the record set.
E)It requires the greatest overhead of any cursor type.

Question 62

Locks that are placed assuming that a conflict will not occur are called:

A)dynamic.
B)explicit.
C)implicit.
D)optimistic.
E)pessimistic.

Question 63

A series of actions to be taken on the database such that either all actions are completed successfully,or none of them can be completed,is known as a:

A)checkpoint.
B)log.
C)lock.
D)transaction.
E)concurrent.

Question 64

Requiring all application programs to lock resources in the same order is a technique for preventing what problem?

A)Concurrent update
B)Lost update
C)Deadlock
D)Exclusive locks
E)Growing phase locking

Question 65

One remedy for the inconsistencies caused by concurrent processing is ________.

A)lost updates
B)checkpointing
C)rollback
D)resource locking
E)concurrency

Question 66

Which type of lock still allows other transactions to have read-only access to the locked resource?

A)Exclusive lock
B)Shared lock
C)Two-phased lock
D)Explicit lock
E)Implicit lock

Question 67

A lock placed automatically by the DBMS is called a(n)________ lock.

A)exclusive
B)explicit
C)granular
D)implicit
E)shared

Question 68

Which of the following is not true about two-phased locking?

A)Can make transactions serializable
B)Uses only shared locks
C)Has a growing phase
D)Has a shrinking phase
E)Cannot obtain a new lock once a lock has been released

Question 69

Which of the following is not true about locks?

A)Locks with large granularity are easier for the DBMS to administer.
B)Locks with small granularity cause more conflicts.
C)Locks with large granularity produce fewer details for the DBMS to track.
D)Locks may have a table-level granularity.
E)Locks may have a database-level granularity.

Question 70

Ensuring that all rows impacted by the actions of a transaction are protected from changes until the entire transaction is completed is called:

A)statement level consistency.
B)optimistic locking.
C)transaction level consistency.
D)durable transactions.
E)ARID transactions.

Question 71

Which type of lock prevents all types of access to the locked resource?

A)Exclusive lock
B)Shared lock
C)Two-phased lock
D)Explicit lock
E)Implicit lock

Question 72

Which of the following is allowed by "Repeatable Read Isolation"?

A)Nonrepeatable reads
B)Dirty reads
C)Phantom reads
D)A and B
E)A,B,and C

Question 73

Measures that are taken to prevent one user's work from inappropriately influencing another user's work are called:

A)concurrency control.
B)checkpoint.
C)database recovery.
D)database logging.
E)interleaving.

Question 74

When a transaction reads a row that has been changed,but the change has not been committed,this is known as a ________.

A)Clean read
B)Dirty read
C)Nonrepeatable read
D)Phantom read

Question 75

The situation that occurs when one user's changes to the database are lost by a second user's changes to the database is known as the:

A)lost update problem.
B)deadly embrace problem.
C)inconsistent read problem.
D)inconsistent write problem.
E)deadlock problem.

Question 76

When two transactions are being processed against the database at the same time:

A)they are called concurrent transactions.
B)they are usually interleaved.
C)they always result in a lost update problem.
D)one must be rolled back.
E)A and B

Question 77

Locks that are placed assuming that a conflict will occur are called:

A)dynamic locks.
B)explicit locks.
C)implicit locks.
D)optimistic locks.
E)pessimistic locks.

Question 78

The situation that occurs when two users are each waiting for a resource that the other person has locked is known as a(n):

A)lost update problem.
B)deadlock.
C)inconsistent read problem.
D)inconsistent write problem.
E)checkpoint.

Question 79

The task of diagnosing errors due to changes in the database structure is eased by:

A)formal policies for requesting changes.
B)database structure change documentation.
C)rollback analysis.
D)configuration control.
E)None of the above.

Question 80

When a transaction rereads data that has been changed and finds changes due to committed transactions,this is known as a ________.

A)Clean read
B)Dirty read
C)Nonrepeatable read
D)Phantom read