Let transaction T1 has obtained a shared mode lock S on data item Q and transaction T2 has obtained an exclusive mode lock X on data item R

Consider the following statement.

I: T1 can read Q but cannot write Q.

II. T2 can read R but cannot write R.

Which of the above statements is / are valid?

Question

Question

Download Solution PDF

Let transaction T1 has obtained a shared mode lock S on data item Q and transaction T2 has obtained an exclusive mode lock X on data item R

Consider the following statement.

I: T1 can read Q but cannot write Q.

II. T2 can read R but cannot write R.

Which of the above statements is / are valid?

This question was previously asked in

HTET PGT Official Computer Science Paper - 2019

Download PDF Attempt Online

View all HTET Papers >

Only I
Only II
Both I and II
Neither I nor II

Answer 1

Concept :

A lock is a variable associated with a data item that describes the status of the data item with respect to possible operations that can be applied to it. They synchronize the access by concurrent transactions to the database items. It is required in this protocol that all the data items must be accessed in a mutually exclusive manner.

Shared Lock: If a transaction Ti has obtained a shared-mode lock (denoted by S) on item Q, then Ti can read, but cannot write, Q.

Exclusive Lock: If a transaction has obtained an exclusive mode lock, then it can both read and write on the item on which it in operating.

Hence Option 1 is correct

Download Solution PDF

Question

Let transaction T1 has obtained a shared mode lock S on data item Q and transaction T2 has obtained an exclusive mode lock X on data item R

Consider the following statement.

I: T1 can read Q but cannot write Q.

II. T2 can read R but cannot write R.

Which of the above statements is / are valid?

Answer (Detailed Solution Below)

Detailed Solution

More Concurrency Control Questions

More DBMS Questions

Question

Let transaction T1 has obtained a shared mode lock S on data item Q and transaction T2 has obtained an exclusive mode lock X on data item R Consider the following statement. I: T1 can read Q but cannot write Q. II. T2 can read R but cannot write R. Which of the above statements is / are valid?

Answer (Detailed Solution Below)

Detailed Solution

More Concurrency Control Questions

More DBMS Questions

Let transaction T1 has obtained a shared mode lock S on data item Q and transaction T2 has obtained an exclusive mode lock X on data item R

Consider the following statement.

I: T1 can read Q but cannot write Q.

II. T2 can read R but cannot write R.

Which of the above statements is / are valid?