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.
Describe the development process of Object oriented methods Object oriented methods have roots which are strongly anchored back in the 60s, functional and structured methods we
What are the ways of obtaining the connection parameters? Hardwire the parameters into the program. Ask for the parameters interactively. Get the parameters
The Assessment page has a link to download a conceptual model, and a list of data. You are to map this conceptual model, and create the database in Oracle using your own DDL. T
anyone have a textbook solutions case fair, 8 edition of vol 1 ?, please give me
Increased parallelism : Since the replicated date has several copies a query can be distributed or can be answered from the smallest loaded site. Also, with more replicas you have
Normal 0 false false false EN-IN X-NONE X-NONE
How can one distinguish among different kinds of parameters? Input parameters are used to pass data to subroutines. Output parameters are used to pass data from subrout
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
Components of database manager The above functions are reached by the database manager. The major elements of a database manager are: Authorisation control: This mod
The indices are accumulated in the index files. The data is accumulated in the data files. Indices give fast access to data items. For example, a book database may be managed in th
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