Transaction states, Database Management System

The following variant of the primary copy asynchronous-update replication protocol has been proposed for totally replicated systems.

(a)  A transaction executing at site A updates only the replicas at A before it commits (it needed to access no other site since replication is total).

(b)  After the transaction commits, a second transaction is initiated to update the primary copies of all items updated at A.

(c)  After the transaction in step (b) has completed, each primary site propagates the update made at that site to all secondaries (including the one at site A). Updates made to a primary copy by several transactions are propagated to secondaries in the order in which the primary was updated.

Explain why, in step (b), all primaries must be updated in a single transaction and, in step (c), the update is propagated to site A.

 

Posted Date: 3/11/2013 1:18:10 AM | Location : United States







Related Discussions:- Transaction states, Assignment Help, Ask Question on Transaction states, Get Answer, Expert's Help, Transaction states Discussions

Write discussion on Transaction states
Your posts are moderated
Related Questions
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 transact

What is data independence? Data Independence: Techniques which permit data to be changed without affecting the applications in which procedure it. There are two types of data

Use a Set operator to create a list of academics who have written or co-written less than 5 papers and also have greater than 3 interests. List their academic number in the output.


Synonyms and Indexes Some of the essential properties of indexes are: An Index is a schema Object Indexes can be formed explicitly or automatically Indexes are m

Index And Tree Structure Let us talk about the data structure that is used for creating indexes. Can we use Binary Search Tree (BST) as Indexes? Let us initial reconsider

What are the comparison operator in SQL?  Comparison operator in SQL are =, LIKE and BETWEEN

Define multivalued dependency and 4NF.  Ans:  Multivalued Dependency - Assume R be a relation schema and let α ⊆ R and β ⊆ R. The multivalued dependency  α →→β   holds o

Create a new user : CREATE USER IDENTIFIED BY Example: //CREATE USER MCA12 IDENTIFIED BY W123 Grant: It is used to give database access permission to users. It is of

What are multiple inheritances? Multiple inheritances allow a class to inherit variables and methods from many super classes.