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"Wound-wait" scheme: It is based on a preemptive method. It is based on a simple rule:
If Ti requests a database resource that is held by Tj
then if Ti has a larger timestamp (Ti is younger) than that of Tj
it is allowed to wait;
else Tj is wounded up by Ti.
For example, suppose that 3 transactions T1, T2 and T3 were generated in that series, then if T1requests for a data item which is presently held by transaction T2, then T2 is rolled back and data item is allotted to T1 as T1 has a smaller time stamping than that of T2. Though, if T3 requests for a data item which is presently held by transaction T2, then T3 is permitted to wait.
Figure: Wound-wait Scheme of Deadlock prevention
It is vital to see that whenever any transaction is rolled back, it would not make a starvation condition, i.e., no transaction gets rolled back repeatedly and is never permitted to make progress. Also both "wait-die" & "wound-wait" idea avoid starvation. The number of aborts & rollbacks will be higher in wait-die scheme than in the wound-wait idea. But one main problem with both of these ideas is that these ideas may result in unnecessary rollbacks.
Mention the purpose of SID and SOD lines SID (Serial input data line): It is an input line by which the microprocessor accepts serial data. SOD (Serial output data line)
What is advantage of two-way association? Two-way association advantages are following: a) Independent of the classes. b) Useful for existing predefined classes that are
losers with new information systems
what is the need of a log in dbms
What does authentication refer? Authentication refers to the task of verifying the uniqueness of a person.
Which two files are used during operation of the DBMS? Data dictionary and transaction log are two files used during operation of the DBMS.
Object-oriented decompositions Object-oriented decompositions of systems better are able to cope with change. Each subsystem has a well-defined interface which communicates with
Using the questions found at the end of Chapter 9 in your textbook, complete this homework activity. Students will submit a Word document answering questions 2, 3, and 4.
how many hourse have been spent on a certain project
Clustering Indexes It may be an excellent idea to keep data of the students in the order of the programme they have registered as most of the data file accesses may need studen
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