Transactions
August 29, 2024UGC NET CS 2006 Dec-paper-2
August 29, 2024Database-Management-System
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Question 612
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Two phase protocol in a database management system is :
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a concurrency mechanism that is not deadlock free
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a recovery protocol used for restoring a database after a crash
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Any update to the system log done in 2-phases
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not effective in Database
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Question 612 Explanation:
The two phase protocol in DBMS refers to a protocol in which locking and unlocking of shared data includes two phases:
1. Growing Phase: In this locks are acquired according to the need as the transaction proceeds.
2. Shrinking Phase: In this release locks as transaction starts reaching to completion.
A transaction can obtain locks but can’t release locks in growing phase. Similarly a transaction can release locks but can’t obtain lock in shrinking phase.
There are various types of two phase locking mechanism which can provide a conflict serializable schedule but can’t provide a schedule which is deadlock free and can be implemented practically.
1. Growing Phase: In this locks are acquired according to the need as the transaction proceeds.
2. Shrinking Phase: In this release locks as transaction starts reaching to completion.
A transaction can obtain locks but can’t release locks in growing phase. Similarly a transaction can release locks but can’t obtain lock in shrinking phase.
There are various types of two phase locking mechanism which can provide a conflict serializable schedule but can’t provide a schedule which is deadlock free and can be implemented practically.
Correct Answer: A
Question 612 Explanation:
The two phase protocol in DBMS refers to a protocol in which locking and unlocking of shared data includes two phases:
1. Growing Phase: In this locks are acquired according to the need as the transaction proceeds.
2. Shrinking Phase: In this release locks as transaction starts reaching to completion.
A transaction can obtain locks but can’t release locks in growing phase. Similarly a transaction can release locks but can’t obtain lock in shrinking phase.
There are various types of two phase locking mechanism which can provide a conflict serializable schedule but can’t provide a schedule which is deadlock free and can be implemented practically.
1. Growing Phase: In this locks are acquired according to the need as the transaction proceeds.
2. Shrinking Phase: In this release locks as transaction starts reaching to completion.
A transaction can obtain locks but can’t release locks in growing phase. Similarly a transaction can release locks but can’t obtain lock in shrinking phase.
There are various types of two phase locking mechanism which can provide a conflict serializable schedule but can’t provide a schedule which is deadlock free and can be implemented practically.