Q&A Hero

Humanities

Q: 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) It requires the greatest overhead of any cursor type.
Q: Which of the following is allowed by "Repeatable Read Isolation"? A) Nonrepeatable reads B) Dirty reads C) Phantom reads D) Both A and B are correct
Q: 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
Q: 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
Q: 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
Q: Locks that are placed assuming that a conflict will not occur are called ________. A) dynamic B) shared C) pessimistic D) optimistic
Q: Locks that are placed assuming that a conflict will occur are called ________. A) explicit locks B) implicit locks C) optimistic locks D) pessimistic locks
Q: 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
Q: 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) checkpoint
Q: Which of the following is not true about two-phased locking? A) Cannot obtain a new lock once a lock has been released B) Uses only shared locks C) Has a growing phase D) Has a shrinking phase
Q: Which type of lock still allows other transactions to have read-only access to the locked resource? A) Exclusive lock B) Shared lock C) Explicit lock D) Implicit lock
Q: Which type of lock prevents all types of access to the locked resource? A) Exclusive lock B) Shared lock C) Explicit lock D) Implicit lock
Q: 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 may have a database-level granularity. D) Locks may have a table-level granularity.
Q: A lock placed automatically by the DBMS is called a(n) ________ lock. A) exclusive B) explicit C) shared D) implicit
Q: One remedy for the inconsistencies caused by concurrent processing is ________. A) concurrency B) checkpointing C) rollback D) resource locking
Q: 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
Q: 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) Both A and B are correct
Q: 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
Q: 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
Q: 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
Q: 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.
Q: Which of the following is not a database administration responsibility of a DBA? A) Managing the database structure B) Writing the applications C) Managing the DBMS D) Maintaining the data repository
Q: A passive data repository is preferred over an active repository because it requires less human intervention.
Q: A standby data repository is one which requires a person to generate the metadata and place it in the repository.
Q: An active data repository is one in which the metadata is automatically created as the system components are created.
Q: The DBA should periodically analyze run-time statistics of database performance to help manage the DBMS.
Q: Both rollforward and rollback require the use of a log of transaction results.
Q: To support rollforward and rollback recovery, transactions must be written to a script before they are applied to the database.
Q: Rollforward and reprocessing are two different names for the same technique.
Q: Rollforward is a method of database recovery that restores the database save and all valid transactions since the save was reapplied.
Q: Reprocessing is normally the most convenient method for recovery after a system failure.
Q: 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.
Q: 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.
Q: A checkpoint is a point of synchronization between the database and the transaction log.
Q: A database save is used to mark the end of a transaction.
Q: The security provided by the DBMS often has to be augmented by additional security features within the application program.
Q: All commercial DBMS products use some version of "username and password" as part of their security features.
Q: Processing rights may be implemented at the DBMS level.
Q: Processing responsibilities should be documented and encoded into manual procedures.
Q: In regard to database security, neither the DBMS nor the database applications can enforce processing responsibilities.
Q: The goal of database security is to ensure that only authorized users can perform authorized activities at authorized times.
Q: 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.
Q: A static cursor processes a snapshot of the relation that was taken when the cursor was opened.
Q: According to ANSI SQL, the serializable isolation level will not allow phantom reads, dirty reads, and nonrepeatable reads.
Q: Repeatable Read isolation is the most restrictive level of isolation.
Q: Nonrepeatable reads occur when a transaction rereads data it has previously read and finds modifications or deletions caused by a committed transaction.
Q: A dirty read happens when one transaction reads a changed record that has not been committed to the database.
Q: Transaction level consistency means that all rows impacted by any actions in a transaction are protected from change during the entire transaction.
Q: A durable transaction is one for which all committed changes are permanent.
Q: The transaction boundaries are the essential information that the DBMS needs from the application programs to enforce different locking strategies.
Q: In general, optimistic locking is the preferred technique for Internet databases.
Q: Resources are locked for a shorter amount of time with pessimistic locking because the transaction is pre-processed.
Q: With pessimistic locking, the assumption is made that a conflict will occur.
Q: With optimistic locking, the assumption is made that no conflict will occur.
Q: Requiring all application programs to lock resources in the same order is one way of preventing a deadlock condition.
Q: Resource locking must be carefully planned because most DBMS products cannot detect a deadlock condition.
Q: In two-phase locking, all locks are released during the contracting phase.
Q: In two-phase locking, all locks are obtained during the growing phase.
Q: Two-phased locking has a growing phase and a shrinking phase.
Q: Two-phased locking is a scheme for achieving serializability of transactions.
Q: Locks with large granularity are easy for the DBMS to administer but frequently cause conflicts.
Q: Explicit locks are locks that are placed automatically by the DBMS.
Q: Locks placed automatically by the DBMS are called implicit locks.
Q: Locks placed by a command issued to the DBMS from the application program are called explicit locks.
Q: Resource locking is one remedy to the lost update problem.
Q: An exclusive lock locks the item from change but not from read access.
Q: An exclusive lock locks the item from access of any type.
Q: The size of a lock is referred to as the lock granularity.
Q: A transaction is a group of alternative database actions, from which the database can choose to perform only one of them.
Q: 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.
Q: A transaction is sometimes called atomic because it is performed as a unit.
Q: Concurrency control measures are taken to ensure that one user's work has absolutely no influence on another user's work.
Q: One important reason for documenting changes to the database structure is for diagnosing errors.
Q: The database is most vulnerable to failure after a change to its structure.
Q: Changes in the database structure usually involve only one application.
Q: The DBA is responsible for managing changes to the database structure, but is rarely involved in the original design of the structure.
Q: The DBA has to find a balance between the conflicting goals of maximizing availability of the database to users and protecting the database.
Q: In general, the overall responsibility of the DBA is to facilitate the development and use of the database system.
Q: Database administration is more important but less difficult in multiuser database systems than in single-user database systems.
Q: Database administration tasks have to be performed for single-user, personal databases.
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