Deck 9: Managing Multiuser Databases

Question 1

Locks placed automatically by the DBMS are called implicit locks.

Answer 1

True

Question 2

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

Answer 2

False

Question 3

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

Answer 3

True

Question 4

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

Question 5

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

Question 6

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

Question 7

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

Question 8

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

Question 9

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

Question 10

Resource locking is one remedy to the lost update problem.

Question 11

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

Question 12

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

Question 13

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

Question 14

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 15

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

Question 16

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

Question 17

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

Question 18

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

Question 19

Changes in the database structure usually involve only one application.

Question 20

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

Question 21

Repeatable Read isolation is the most restrictive level of isolation.

Question 22

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

Question 23

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

Question 24

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

Question 25

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

Question 26

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

Question 27

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

Question 28

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

Question 29

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

Question 30

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 31

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

Question 32

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

Question 33

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

Question 34

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

Question 35

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

Question 36

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

Question 37

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

Question 38

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

Question 39

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

Question 40

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

Question 41

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

Question 42

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

Question 43

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

Question 44

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 45

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

Question 46

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

Question 47

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

Question 48

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

Question 49

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

Question 50

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

Question 51

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

Question 52

Processing rights may be implemented at the DBMS level.

Question 53

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

Question 54

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

Question 55

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 56

Processing responsibilities should be documented and encoded into manual procedures.

Question 57

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 58

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

Question 59

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 60

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

Question 61

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 62

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 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

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 65

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

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

Question 66

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 67

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 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 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 70

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 71

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 72

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 73

Which of the following cannot be enforced in the DBMS or application programs?

A)processing rights
B)security
C)processing responsibilities
D)cursors
E)transaction isolation

Question 74

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 75

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

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

Question 76

Once processing rights have been defined,they may be implemented at any of these levels except:

A)network.
B)operating system.
C)data.
D)DBMS.
E)application.

Question 77

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

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

Question 78

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 79

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 80

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