Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Exclusive lock
Let us explain the above two modes with the help of an instance. We will once again consider the transactions T1 and T2 but in addition a transaction T11 that search the total of accounts Y and Z.
Schedule
T1
T2
T11
S_Lock X
S_Lock Y
Read X
S_Lock Z
Read Y
Read Z
X_Lock X
X_Lock X. The exclusive lock request on X is denied as T2 holds the Read lock. The transaction T1 Waits.
Display X+Y
Unlock X
X_Lock Y
X_Lock Y. The previous exclusive lock request on X is granted as X is unlocked. But the new exclusive lock request on Y is not granted as Y is locked by T2 and T11 in read mode. Thus T1 waits till both T2 and T11 will release the read lock on Y.
Display Y+Z
Unlock Y
Unlock Z
Subtract 100
Write X
Add 100
Write Y
Figure: Example of Locking in multiple-modes
Therefore, the locking as above results in a serialisable schedule. Now the query is can we release locks a bit early and have still no concurrency related problem?Yes, we can do it if we lock using two-phase locking protocol.
Advantages of Observation Methods: Bailey has pointed out four advantages of observation: 1. Superior in Data Collection on Non Verbal Behavior: When a person a opi
Critically evaluate the bulleted list of information-related items in this case study. How are each contradictory to the notion of being an information-literate knowledge worker?
Describe an data dictionary? A data dictionary is a data structure which keeps meta data about the structure of the database ie. the schema of the database.
Have a look around the site, and at some of the sites they have featured. These are all examples of bad design, and also offer an explanation about why they fall into this category
Explain in detail about Collaboration Diagrams Collaboration diagrams are interaction diagrams which emphasize structural organisation of an object that transmit and receive m
Write short notes on relational model The relational model uses a collection of tables to show both data and the relationships between those data. The relational model is an ex
Name the metrics for selecting top algorithm There are a number of metrics for selecting top algorithm: i) Computational complexity: Computational complexity refers to eff
What is the role of ORDER By Clause? ORDER BY clause: The ORDER BY clause permits you to sort the records in your result set. The ORDER BY clause can just be used in select s
Lack of standards and experience: The lack of standards has considerably limited the potential of distributed DBMSs. As well, there are no tools or methodologies to help users cha
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 updat
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!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd