Database System Concepts
7th Edition
ISBN: 9781260084504
Author: Abraham Silberschatz, S. Sudarshan, Abraham, Henry Korth, Silberschatz Abraham, Silberschatz Professor
Publisher: McGraw-Hill Education
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Expert Solution & Answer
Chapter 23, Problem 11PE
Explanation of Solution
a.
Federated
- At some location, we can have special data items on which the lock will be obtained before starting a global transaction.
- The lock must be released after the completion of the transaction. This ensures the single active global transaction requirement...
Explanation of Solution
b.
Example for a non-serializable global schedule:
The following schedule includes 2 sites and 4 transactions.
- T1 and T2 are the local transactions that are running at site1 and site2 respectively.
- TG1 and TG2 are the global transactions that are running at both sites.
- X1, Y1 area data items at site1, and X2, Y2 are at site2.
| T1 | T2 | TG1 | TG2 |
| write(Y1) | |||
| read(Y1) | |||
| ... |
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