Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Serialisable Schedules:If the processes of two transactions conflict with each other, how to verify that no concurrency related problems have happened? For this, serialisability theory has been developed. Serialisability theory attempts to verify the correctness of the schedules. The rule of this theory is:
"A schedule S of n transactions is serialisable if it is equal to some serial schedule of the similar 'n' transactions".
A serial schedule is a schedule in which either transaction T1 is totally done before T2 or transaction T2 is totally done before T1. For instance, the following figure clears the two possible serial schedules of transactions T1 & T2.
Schedule A: T2 followed by T1
Schedule B: T1 followed by T2
Schedule
T1
T2
Read X
Read Y
Subtract 100
Display X+Y
Write X
Add 100
Write Y
Figure: Serial Schedule of two transactions
Schedule C: An Interleaved Schedule
Figure: An Interleaved Schedule
Now, we have to figure out whether this interleaved schedule would be performing read and write in the same order as that of a serial schedule. If it does, then it is equivalent to a serial schedule, otherwise not. In case it is not equivalent to a serial schedule, then it may result in problems due to concurrent transactions.
Example : Search the name, department number and salary of employees drawing minimum salary in that department. SELECT ENAME, SAL, DEPTNO FROM EMP WHERE SAL IN (SELECT MI
Question 1 Explain the 10 reasons to use MySQL Question 2 Write the SQL statements to demonstrate the following using SELECT command Expression Evaluation ORDER BY
List some instances of collection types? a) sets b) arrays c) multisets
Do NOT use the timestamp type. Use separate date and time data types only. Figure out how to define an SQL insert statement that uses built-in SQL (or MySQL) functions to define
Submission Requirements All answers must be computer generated (including text and diagrams). The hand-in version must include a header page (or with sufficient space)
What is a hashing function? What are the properties of a good hashing function? Describe the folding technique for hashing functions. Ans: Hashing function is a method
Run the following queries. For each query show 1) What you expect the output to be based upon the data 2) the SQL code and 3) the output running the query in Oracle. 1. Show all c
Can a domain, assigned to a data element be changed? Yes. We can do so by just overwriting the entry in the field domain.
What is a trigger
Process to find the non-concurrent objects Once we find out non-concurrent (mutually exclusive) objects, we can fold all objects together in one thread of process or control. O
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd