Explain strict two-phase locking, Database Management System

Assignment Help:

Explain Strict Two-Phase locking

A transaction T does not release any type of its exclusive (X) locks until that transaction commits or aborts. In this method no other transaction can access the item which is written by T unless the transaction T commits. This is a better method than the two discussed.

In 2PL, a transaction may not be capable to release its locks even after make use of it. The data item will stay locked until the transaction ends all the actions on all the data items. If each transaction in a schedule follows 2PL after that conflict serializability can be made sure. This is since if the schedule is not serializable, the precedence graph for schedule S contains transactions T1, T2 ..... Tn will have a cycle ... assume that a cycle consists of T1, T2 ..... Tn ,T1.  The meaning of this is that a lock operation by T2 is followed by an unlock operation by T1; A Lockoperation T3 is followed by an unlock operation by T2 ... and etc.  Though this is a contradiction of the assertion that T1 is by using two phase locking protocol. So the assumption that graph is having a cycle is wrong and therefore S is serializable.


Related Discussions:- Explain strict two-phase locking

File organization, what is file organization? what are file organization te...

what is file organization? what are file organization techniques.explain in detail? explain random file organization technique, multikey file organization technique?what is indexin

When are two schedules said to be view equivalent, When are two schedules s...

When are two schedules said to be view equivalent?     Ans: Two schedules that is denoted as S and S' are said to be view equivalent if the subsequent three conditions are met

Function module and a normal abap/4 subroutine, What is the difference betw...

What is the difference between the function module and a normal ABAP/4 subroutine? In contrast to normal subroutines function modules have uniquely exact interface.  Declaring da

Log based recovery, Log based recovery: Let us first describe the term tran...

Log based recovery: Let us first describe the term transaction log in the context of DBMS. A transaction log is a record in DBMS that remains track of all the transactions of a dat

What is a b+-tree index, What is a B+-Tree index? A B+-Tree index takes...

What is a B+-Tree index? A B+-Tree index takes the form of a balanced tree in which each path from the root of the root of the root of the tree to a leaf of the tree is of the

What is the meaning of data independence, What is the meaning of Data indep...

What is the meaning of Data independence? Data independence means a programs that are not dependent on the physical attributes of data and a programs that are not dependent on

Extended star schema, Why did SAP introduce the extended star schema? Expla...

Why did SAP introduce the extended star schema? Explain why it is reported to be better than the traditional schema model?

Consider relational schema and construct algebra query, Consider the follow...

Consider the following relational schema: PERSON (SS#, NAME, ADDRESS) CAR (REGISTRATION_NUMBER, YEAR, MODEL) ACCIDENT (DATE, DRIVER, CAR_REG_NO) OWNS (SS#, LICENSE) Constru

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

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!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd