Explain a database lockout and the deadlock phenomenon. Contrast that to concurrency control and the timestamping technique. Describe the importance of these items in relation to database integrity
In a centralized database, a database lockout is used to ensure data currency. It is a software control that prevents multiple simultaneous access to data. Upon receiving a data access request, the central site DBMS places a lock on the requested data to prevent additional access until the lock is removed.
In a distributed environment it is possible that multiple sites will lock each other out, preventing each from processing its transactions. This results in a deadlock because there is mutual exclusion to data and the transactions are in a wait state until the locks are removed. A deadlock is a permanent condition that must be resolved by special software that analyzes each deadlock to determine the best solution.
In a replicated database, a large volume of data flows between sites, and temporary inconsistencies in the database may occur. Database concurrency is the presence of complete and accurate data at all remote sites. A commonly used method for concurrency control is to serialize and timestamp transactions that are in conflict.
Both database lockouts and concurrency controls are designed to ensure that the transactions are completely processed and that all transactions are accurately reflected in the firm's databases. Failure to implement these controls can result in transactions being lost, being partially processed, or with inconsistent databases.
You might also like to view...
During a meeting to discuss ways to cut costs on benefits packages, the vice president of the company, Ian, suggests getting long-term disability insurance for all employees. Patty, the HR manager, disagrees with him, stating that short-term disability coverage is more advantageous for the company. Which of the following supports Patty's statement?
A. Short-term disability plans limit maximum coverage in a month, which makes them more affordable for the company. B. Short-term disability coverage is offered by few employers, which leads to a competitive advantage. C. The nature of work is such that the level of risk involved is high and injuries could be permanent. D. The majority of the workforce is middle-aged and prefers long-term coverage. E. Long-term disability coverage does not have any limits on the amount to be paid each month to employees.
Slotkin Company buys designer clothing to sell in its retail stores. Since much of the merchandise comes from Dallas and Europe, Slotkin Company must pay freight charges to get the merchandise shipped in. Which statement is true?
a. Transportation-in, paid by Slotkin Company, is added to the inventory account under the periodic system. b. Transportation-in, paid by Slotkin Company, is subtracted from purchases under the periodic system. c. Freight charges are only paid by a buyer in a periodic system. d. Transportation-in is added to net purchases to determine cost of goods purchased in a periodic system.
Only one copy of the prelist should be prepared when an employee opens mail with customer payments to avoid complexity in the accounting system and maintain control
a. True b. False Indicate whether the statement is true or false
Deposits made directly by the bank would be
A. added to the company's records. B. deducted from the company's records. C. added to the bank statement balance. D. deducted from the bank statement balance.