Database Management System · Unit 9 · 4 hrs
Concurrency Control Techniques
Exam-focused notes for Concurrency Control Techniques (Database Management System, CSC265): what the TU syllabus asks and how it has actually been tested, with 9 solved past questions from this unit.
What this unit covers
- Two-Phase Locking Technique
- Timestamp Ordering
- Multiversion Concurrency Control
- Validation (Optimistic) Techniques and Snapshot Isolation Concurrency Control
Two-Phase Locking Technique
What is two-phase locking? What are different types of locks in two-phase locking? Explain basic, conservative, strict, rigorous two-phase locking. What is lock conversion?[10]
A transaction is said to follow the two-phase locking (2-PL) protocol if all locking operations (read-lock, write-lock) precede the first unlock operation in the transaction. Locking is an operation which secures permission to read or permission to write a ...
Full solved answer →Why do we need concurrency control in databases? Explain. [5]
Concurrency Control is the management procedure required for controlling the execution of operations that take place on a database simultaneously. It is a procedure of managing simultaneous operations without conflicting with each other. --- A DBMS must all...
Full solved answer →What is concurrency control? What are its advantages in DBMS? [5]
Concurrency Control is the management procedure in DBMS for managing simultaneous operations without conflicting with each other. It is required for controlling the concurrent execution of operations that take place on a database. A DBMS must allow multiple...
Full solved answer →What is concurrency control? Name various methods of controlling the concurrency control? Differentiate between Binary lock and shared/Exclusive lock.[10]
Concurrency Control is the management procedure required for controlling the concurrent execution of operations that take place on a database. It is a procedure of managing simultaneous operations without conflicting with each other. - To apply isolation th...
Full solved answer →What is Granularity of data items? How does it effect in concurrency control? [5]
A database is basically represented as a collection of named data items. The size of a data item is called its granularity. A data item can be defined at different levels of size, for example: Granularity Level Example ------ Fine (Small) An individual fiel...
Full solved answer →Explain 2 phase locking technique in brief. [5]
Locking is an operation which secures permission to read or permission to write a data item. Two Phase Locking (2PL) is a concurrency control protocol that ensures serializability by regulating when transactions may lock and unlock data items. A transaction...
Full solved answer →Explain deadlock with example. What are different deadlock prevention protocols? Explain deadlock detection and starvation.[10]
Deadlock is a condition in a database system (or operating system) where no process proceeds for execution and each process waits for resources that have been acquired by other processes. In other words, a set of transactions are permanently blocked, each w...
Full solved answer →Timestamp Ordering
Explain deadlock and starvation. Explain Time stamp based protocol for concurrency control?[10]
--- Deadlock is a situation in a database system where two or more transactions are waiting indefinitely for each other to release locks on data items, so that none of them can ever proceed. - Transaction T1 holds a lock on item X and waits for a lock on it...
Full solved answer →How timestamp ordering protocol is used for ensuring concurrency control? [5]
A timestamp is a unique identifier assigned to each transaction by the DBMS, typically based on the system clock or a logical counter at the time the transaction starts. The timestamp ordering protocol uses these timestamps to determine the serialization or...
Full solved answer →Make Unit 9 stick
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