The world’s Largest Sharp Brain Virtual Experts Marketplace Just a click Away
Levels Tought:
Elementary,Middle School,High School,College,University,PHD
| Teaching Since: | May 2017 |
| Last Sign in: | 409 Weeks Ago |
| Questions Answered: | 66690 |
| Tutorials Posted: | 66688 |
MCS,PHD
Argosy University/ Phoniex University/
Nov-2005 - Oct-2011
Professor
Phoniex University
Oct-2001 - Nov-2016
Suppose the deferred modification technique is used in a database.
a. Is the old-value part of an update log record required any more? Why or why not?
b. If old values are not stored in update log records, transaction undo is clearly not feasible. How would the redo-phase of recovery have to be modified as a result?
c. Deferred modification can be implemented by keeping updated data items in local memory of transactions, and reading data items that have not been updated directly from the database buffer. Suggest how to efficiently implement a data item read, ensuring that a transaction sees its own updates. d. What problem would arise with the above technique, if transactions perform a large number of updates?
Hel-----------lo -----------Sir-----------/Ma-----------dam-----------Tha-----------nk -----------You----------- fo-----------r u-----------sin-----------g o-----------ur -----------web-----------sit-----------e a-----------nd -----------and----------- ac-----------qui-----------sit-----------ion----------- of----------- my----------- po-----------ste-----------d s-----------olu-----------tio-----------n.P-----------lea-----------se -----------pin-----------g m-----------e o-----------n c-----------hat----------- I -----------am -----------onl-----------ine----------- or----------- in-----------box----------- me----------- a -----------mes-----------sag-----------e I----------- wi-----------ll