Managing Multiuser Databases Questions

• Two transactions that run concurrently and generate results that are consistent with the results that would have occurred if they had run separately are referred to as serializable transactions.
• A point of synchronization between the database and the transaction log is generally referred to as a stop point.
• A phantom read occurs when a transaction rereads data it has previously read and finds modifications or deletions caused by a committed transaction.
• A transaction is a series of actions to be taken on the database so that either all of them are performed successfully or none of them are performed at all.
• The overall responsibility of the DBA is to facilitate the development and use of the database.
• When two transactions are being processed against the database at the same time they are termed concurrent transactions.
• The size of the lock is referred to as the lock granularity.
• An ACID transaction is one that is atomic, consistent isolated, and durable.
• A durable transaction is one in which all committed changes are permanent.
• An exclusive lock locks the item from change but not from read.
• Database administration refers to a function that applies to the entire organization.
• Locks placed by command are implicit locks.
• The size of a lock is referred to as lock sizing.
• The goal of database security is to ensure that only authorized users can perform authorized activities at authorized times.
• Resource locking is a process to prevent multiple applications from obtaining copies of the same record when the record is about to be changed.
• In optimistic locking, the assumption is made that conflict will occur.
• When one transaction reads a changed record that has not been committed to the database a filthy read occurs.
• The transaction log contains a copy of every database record (or page) after it has changed. These records are called before images.
• The lost update problem is when User A reads data that have been processed by a portion of a transaction from User B.
• Locks placed by the DBMS are explicit locks.