DMC1971 Anna University MCA Distance Education Question Paper

Anna University MCA Distance Education Advanced Databases Question Paper / Anna University MCA Distance Education Advanced Databases Question Paper / Anna University MCA Distance Education Previous Year Question Paper / DMC 1971 Advanced Databases Question Papers with Answers / DMC 1625 Advanced Databases Question Papers with Answers / DMC1971 and DMC1625 Previous Year Question Papers

DMC 1971 - Advanced Databases

(Regulation 2009)

DMC 1971 Advanced Databases, August 2013 DMC 1971 Advanced Databases, February/March 2013 DMC 1971 Advanced Databases, August 2012 DMC 1971 Advanced Databases, February 2012 DMC 1971 Advanced Databases, August 2011 DMC 1971 Advanced Databases, February 2011

Click Here

DMC 1971 Advanced Databases, February 2014 - Click Here

DMC 1625 - Advanced Databases

(Regulation 2007)

DMC 1625 - Advanced Databases, August 2013 DMC 1625 - Advanced Databases, February/March 2013 DMC 1625 - Advanced Databases, August 2012 DMC 1625 - Advanced Databases, February 2012 DMC 1625 - Advanced Databases, August 2011 DMC 1625 - Advanced Databases, February 2011 DMC 1625 - Advanced Databases, August 2010 DMC 1625 - Advanced Databases, February 2010

Click Here

DMC1913 Anna University MCA Distance Education Question Paper

Anna University MCA Distance Education Database Management Systems Question Paper / Anna University MCA Distance Education Advanced Databases Question Paper / Anna University MCA Distance Education Previous Year Question Paper / DMC 1913 Database Management Systems Question Papers with Answers / DMC 1654 Database Management Systems Question Papers with Answers / DMC1913 and DMC1654 Previous Year Question Papers

DMC 1913 - Database Management Systems

(Regulation 2009)

DMC 1913 - Database Management Systems, February/March 2013 DMC 1913 - Database Management Systems, August 2012 DMC 1913 - Database Management Systems, February 2012 DMC 1913 - Database Management Systems, August 2011 DMC 1913 - Database Management Systems, February 2011 DMC 1913 - Database Management Systems, August 2010 DMC 1913 - Database Management Systems, February 2010

Click Here

DMC 1654 - Database Management Systems

(Regulation 2007)

DMC 1654 - Database Management Systems, February 2012 DMC 1654 - Database Management Systems, February 2010 DMC 1654 - Database Management Systems, February 2008

Click Here

Centralized deadlock detection approach in distributed database

Centralized deadlock detection technique / How to handle deadlock detection in distributed database? / False cycle in distributed database deadlock detection / What is false cycle?

 

Centralized deadlock detection approach

This is the technique used in distributed database system to handle deadlock detection. According to this approach, the system maintains one Global wait-for graph in a single chosen site, which is named as deadlock-detection coordinator. The Global wait-for graph is updated during the following conditions;

• Whenever a new edge is inserted or removed in the local wait-for graphs of any sites.

• Periodically

• Whenever the coordinator invokes the detection algorithm.

How does it work?

When the deadlock-detection coordinator starts the deadlock-detection algorithm, it searches for cycles. If the coordinator finds a cycle, then the following will happen;

• The coordinator selects a victim transaction that need to be rolled back.
• The coordinator informs about the victim transaction to all the sites in the distributed database.
• The sites rollback the transaction.

This approach (centralized detection approach) may lead to unnecessary rollbacks due to one of the following; (the main cause is the communication delay.)

1. False cycles -

2. Individual transaction rollback during a deadlock and a victim is chosen – for example; let us assume that a deadlock occurred in a distributed database. Then the coordinator chooses one victim transaction and informs the sites about the victim to rollback. At the same time, because of some other reasons, a transaction Ti rollback itself. Now the whole system performed unnecessary rollbacks.


 

*************

Go to Deadlock handling in Distributed Database home

What is Centralized deadlock detection approach in distributed database