Database Systems, unit: Transactions and Concurrency Control. Core concepts, terminology, and worked-example cues a college student meets for this unit, building on prior units without repeating them. Front: a term, concept, or short problem cue. Back: the definition, explanation, or answer.
18 cards · basic cards · AI-written, checked twice. Edit anything.
- What is a database transaction?
- A sequence of operations performed as a single logical unit of work
- What does ACID stand for?
- Atomicity, Consistency, Isolation, and Durability
- What is atomicity, in ACID?
- A transaction either fully completes or has no effect at all
- What is consistency, in ACID?
- A transaction brings the database from one valid state to another
- What is isolation, in ACID?
- Concurrent transactions do not interfere with each other's intermediate states
- What is durability, in ACID?
- Once a transaction commits, its changes persist even after a system failure
- What is a commit, in a transaction?
- An operation that permanently saves all changes made during a transaction
- What is a rollback, in a transaction?
- An operation that undoes all changes made during an incomplete or failed transaction
- What is concurrency control?
- Techniques ensuring correct results when multiple transactions run simultaneously
- What is a race condition, in database terms?
- An error caused by unsynchronized concurrent access to shared data
- What is a lock, in concurrency control?
- A mechanism that restricts access to data to prevent conflicting concurrent operations
- What is a deadlock, in database transactions?
- A situation where two or more transactions wait indefinitely for each other's locks
- What is a dirty read?
- Reading uncommitted data from another transaction that may later be rolled back
- What is a non-repeatable read?
- Reading the same row twice within a transaction and getting different values
- What is a phantom read?
- A transaction reads a set of rows twice and finds new rows added by another transaction
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