Chapter 10 Flashcards
Most real-world database transactions are formed by only one database request.
false
The DBMS guarantees that the semantic meaning of a transaction truly represents the real-world event.
false
Atomicity indicates the permanence of the database’s consistent state.
false
The multiuser DBMS must implement controls to ensure serializability and isolation of transactions, in addition to atomicity and durability, in order to guard the database’s consistency and integrity.
true
Durability requires that all portions of the transaction must be treated as a single, logical unit of work in which all operations are applied and completed to produce a consistent database.
false
In a page-level lock, the DBMS will lock an entire diskpage.
true
A shared lock produces no conflict as long as all the concurrent transactions are read-write only.
false
When using an optimistic approach, a transaction reads the database, executes the needed computations, and makes the updates to a private copy of the database values.
true
An optimistic approach is based on the assumption that the majority of the database operations do not conflict.
true
The last step in the write-through technique recovery procedure is to identify the last checkpoint in the transaction log.
false
A transaction is a ____ unit of work that must be either entirely completed or aborted.
timed
practical
-logical
physical
____ means that data used during the execution of a transaction cannot be used by a second transaction until the first one is completed.
Serializability
Atomicity
-Isolation
Time stamping
All transactions must display ____.
atomicity, consistency, and durability
durability and isolation
consistency, durability, and isolation
-atomicity, durability, consistency, and isolation
ANSI defines four events that signal the end of a transaction. Of the following events, which is defined by ANSI as being equivalent to a COMMIT?
Five SQL statements are executed.
-The end of a program is successfully reached.
The program is abnormally terminated.
The database is shut down for maintenance.
ANSI defines four events that signal the end of a transaction. Of the following events, which is defined by ANSI as being equivalent to a ROLLBACK?
Five SQL statements are executed.
The end of a program is successfully reached.
-The program is abnormally terminated.
The database is shut down for maintenance.
One of the three most common data integrity and consistency problems is ____.
-lost updates
disk failures
user errors
deadlocks
As long as two transactions, T1 and T2, access ____ data, there is no conflict, and the order of execution is irrelevant to the final outcome.
shared
common
-unrelated
locked
The ____ manager is responsible for assigning and policing the locks used by the transactions.
transaction
database
-lock
schedule
Lock ____ indicates the level of lock use.
-granularity
shrinking
growing
serializability
A diskpage, or page, is the equivalent of a ____.
database table
disk sector
database schema
-diskblock
A ____ lock allows concurrent transactions to access different rows of the same table.
database-level
table-level
page-level
-row-level
A(n) ____ lock exists when concurrent transactions are granted read access on the basis of a common lock.
-shared
exclusive
binary
two-phase
What is a rule that applies to the two-phase locking protocol?
-Two transactions cannot have conflicting locks.
No unlock operation can precede a lock operation in a different transaction.
No data is affected until all locks are released.
No data is affected until the transaction is in its locked position.
The ____ approach to scheduling concurrent transactions assigns a global unique stamp to each transaction.
scheduled
table-locking
unique
-timestamping
Although the DBMS is designed to recover a database to a previous consistent state when an interruption prevents the completion of a required set of transactions, the transactions themselves are defined by the end user or programmer and must be semantically correct.
true
Atomicity indicates the permanence of the database’s consistent state.
false
Incomplete or improper transactions can have a devastating effect on database integrity.
true
The scheduler establishes the order in which the operations within concurrent transactions are executed.
true
A shared lock produces no conflict as long as all the concurrent transactions are read-write only.
false
A growing phase in a two-phase lock is when a transaction acquires all the required locks without locking any data.
false
____ requires that all operations of a transaction be completed.
Specificity
-Atomicity
Durability
Time stamping
The ANSI has defined standards that govern SQL database transactions. Transaction support is provided by two SQL statements: ____ and ROLLBACK.
RETRIEVE
ASSIGN
UPDATE
-COMMIT
The information stored in the ____ is used by the DBMS for a recovery requirement triggered by a ROLLBACK statement, a program’s abnormal termination, or a system failure such as a network discrepancy or a disk crash.
data dictionary
metadata
rollback manager
-transaction log
As long as two transactions, T1 and T2, access ____ data, there is no conflict, and the order of execution is irrelevant to the final outcome.
shared
common
-unrelated
locked
____ are required to prevent another transaction from reading inconsistent data.
-Locks
Schedules
Stamps
Logs
A ____ lock locks the entire diskpage.
transaction-level
table-level
-page-level
row-level
A ____ lock allows concurrent transactions to access different rows of the same table.
database-level
table-level
page-level
-row-level
A(n) ____ specifically reserves access to the transaction that locked the object.
shared lock
-exclusive lock
binary lock
deadlock
A(n) ____ condition occurs when two or more transactions wait for each other to unlock data.
-deadlock
exclusive lock
binary lock
two-phase lock
