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Questions and Answers
What describes a transaction in a DBMS?
What describes a transaction in a DBMS?
Which property ensures that transactions are treated as a single unit of work?
Which property ensures that transactions are treated as a single unit of work?
What is a serial schedule in transaction management?
What is a serial schedule in transaction management?
What does a serializable schedule represent?
What does a serializable schedule represent?
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What happens if a transaction aborts in a DBMS?
What happens if a transaction aborts in a DBMS?
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Study Notes
Transactions Overview
- Concurrent execution of user programs enhances DBMS performance.
- A transaction acts as an abstract representation of a user's operations, focusing on database read/write activities.
Concurrency in DBMS
- Users perceive each transaction as executing independently.
- The DBMS manages concurrency by interleaving actions (reads and writes) of multiple transactions.
- Transactions must maintain database consistency, ensuring the database remains in a consistent state post-execution.
Atomicity of Transactions
- Transactions can either commit after all actions are executed or abort before completion.
- Atomicity is a critical property ensured by the DBMS, meaning that either all actions are completed, or none are applied.
- The DBMS logs transaction actions, enabling it to revert any changes made by aborted transactions.
Example of Transactions
- Two transactions example:
- T1: Increments A by 100 and decrements B by 100.
- T2: Multiplies A and B by 1.06.
- There is no guaranteed execution order between T1 and T2; however, their net effect must mirror the result of executing them sequentially.
Scheduling Transactions
- Serial Schedule: A type of scheduling where transaction actions do not intermingle.
- Equivalent Schedules: Two schedules are considered equivalent if executing them yields the same database state.
- Serializable Schedule: A schedule that can be rearranged to match the outcome of some serial execution of transactions.
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Description
Explore the intricacies of transaction management in database systems in this quiz. Delve into the concepts of concurrent execution and the importance of transactions in maintaining database integrity. Test your understanding of how DBMS handles multiple operations efficiently.
