Database Management System · Unit 7
Transaction Management
Exam-focused notes for Transaction Management (Database Management System, BIT202): what the TU syllabus asks and how it has actually been tested, with 8 solved past questions from this unit.
What this unit covers
- Transaction definition
- ACID properties
- Transaction states and state diagram
- Serial and non-serial schedules
- Serializable schedules
- Conflict serializability testing
- Lost update problem
- Dirty read problem
- Incorrect summary problem
Lost update problem
What is a transaction? Describe how lost update and dirty read problems occur in concurrent execution of transactions? Illustrate with examples.[10]
A transaction is a logical unit of work that consists of a sequence of database operations (such as read and write) that must be executed as a single, indivisible unit. A transaction either completes fully (commits) or has no effect at all (rolls back). A t...
Full solved answer →Show how lost update and incorrect summary problem might occur in concurrent execution of transactions. [5]
The lost update problem occurs when two transactions read the same data item and then both update it, causing one transaction's update to be overwritten (lost) by the other. Let X = 100 (a bank account balance). Two transactions T1 and T2 execute concurrent...
Full solved answer →Serial and non-serial schedules
Define serial, non-serial and serializable schedules with example. How can you test serializability in a schedule? Explain with an example.[10]
A serial schedule is one in which transactions are executed one after another, without any interleaving of operations. One transaction must complete entirely before the next one begins. Properties: - No concurrency - Always consistent (correct by definition...
Full solved answer →What is Schedule? Explain Serializability and Conflict Schedule. [5]
--- A schedule is a sequence of operations (read, write, commit, abort) from one or more concurrent transactions, arranged in the order they are executed by the system. - If transactions T1, T2, ..., Tn execute concurrently, a schedule defines the interleav...
Full solved answer →Define serial, non-serial and serilizable schedules with example. How can you test serializability in a schedule, illustrate with an example?[5]
A schedule in which transactions are executed one after another, without any interleaving of operations. One transaction completes fully before the next begins. Example (Serial Schedule S1): T1 T2 -------- Read(A) Write(A) Read(B) Write(B) Read(A) Write(A) ...
Full solved answer →Transaction states and state diagram
What is Transaction? State and explain the states of transaction with transition diagram.[5]
A transaction is a logical unit of work or a sequence of operations performed on a database that must be executed as a whole. It is a collection of database operations (such as read, write, insert, update, delete) that together form a single logical unit. A...
Full solved answer →What is Transaction? Draw a Transaction state diagram and discuss the typical state that a transaction goes through during execution.[10]
A transaction is a logical unit of work that consists of a sequence of one or more database operations (such as read, write, insert, update, or delete) that must be executed as a single, indivisible unit. A transaction either executes completely or not at a...
Full solved answer →Transaction definition
What is Transaction? State and explain the properties of Transaction.[5]
A transaction is a logical unit of work that consists of a sequence of one or more database operations (such as read, write, insert, update, or delete) that must be executed as a single atomic unit. A transaction either completes fully or does not execute a...
Full solved answer →Make Unit 7 stick
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