Exam (elaborations)
UTA INSY 3304 – CHAPTER 10 EXAM
- Course
- Institution
UTA INSY 3304 – CHAPTER 10 EXAM...
[Show more]
Content preview
Transaction - ANSWER A logical unit of work that must be entirely completedor aborted
Atomicity - ANSWER All operations of a transaction must be completed; if not
the transaction is aborted
Consistency - ANSWER Permanence of database's consistent state
Isolation - ANSWER Data used during a transaction cannot be used by the
second transaction until the first is completed
Durability - ANSWER Ensures that once transactions are committed they
cannot be undone or lost
Serializability - ANSWER Ensures that the schedule for the concurrent
execution of several transactions should yield consistent results
Transaction Log - ANSWER Keeps track of all transactions that update the
database
DBMS uses the information stored in a log for (a):
- Recovery requirement triggered by a ROLLBACK statement
- Program's abnormal termination
- System failure
Concurrency Control - ANSWER Coordination of the simultaneous transactions
execution in a multiuser database system
• Objective: ensures serializability of transactions in a multiuser database
environment
Problems in Concurrency Control - ANSWER Lost update, uncommitted data,
inconsistent retrievals
, Scheduler - ANSWER Establishes the order in which the operations are
executed within concurrent transactions
- Creates serialization schedule
Locking methods - ANSWER facilitate isolation of data items used in
concurrently executing transactions
Lock - ANSWER guarantees exclusive use of a data item to a current
transaction
Pessimistic locking - ANSWER use of locks based on the assumption that
conflict between transactions is likely
Lock manager - ANSWER responsible for assigning and policing the locks used
by the transactions
Lock Granularity - ANSWER - indicates level of lock use
- levels: database, table, page, row, or field (attribute)
Binary lock - ANSWER A lock that has only two states: locked (1) and
unlocked (0). If a data item is locked by a transaction, no other transaction can
use that data item.
Exclusive lock - ANSWER Access is reserved for the transaction that locked
the object
Shared lock - ANSWER Concurrent transactions are granted read access on the
basis of a common lock
Problems using locks - ANSWER - resulting transaction schedule might not be
serializable
- schedule might create deadlocks
Two-Phase Locking to Ensure Serializability - ANSWER Defines how
transactions acquire and relinquish locks
• Guarantees serializability but does not prevent deadlocks
Phases
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller Boostertips. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $10.49. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
75632 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now