Database Systems Chapter 21 Quiz

<p>Locked and Unlocked (A)</p> Signup and view all the answers

<p>To request access to data item X. (C)</p> Signup and view all the answers

<p>By not using locks, which eliminates the possibility of circular wait conditions. (B)</p> Signup and view all the answers

<p>Shared/exclusive locks allow read operations to occur concurrently, while binary locks do not. (B)</p> Signup and view all the answers

<p>Incrementing a counter or using the system clock. (D)</p> Signup and view all the answers

<p>Exclusive Lock (B)</p> Signup and view all the answers

<p>The schedules produced are conflict serializable. (D)</p> Signup and view all the answers

<p>modify_lock(X) (B)</p> Signup and view all the answers

<p>Ensuring schedules are both strict and conflict serializable. (A)</p> Signup and view all the answers

<p>It prevents concurrent read access. (D)</p> Signup and view all the answers

<p>Issuing a write_lock operation after a read_lock operation. (C)</p> Signup and view all the answers

<p>The shrinking phase. (A)</p> Signup and view all the answers

<p>Expanding Phase (A)</p> Signup and view all the answers

<p>The schedule will be serializable. (C)</p> Signup and view all the answers

<p>It might prevent some serializable schedules from occurring. (D)</p> Signup and view all the answers

<p>Transactions lock all needed items before starting. (C)</p> Signup and view all the answers

<p>Conservative (static) 2PL (C)</p> Signup and view all the answers

<p>Strict 2PL does not release exclusive locks until after commit or abort, while Basic 2PL can release them earlier. (D)</p> Signup and view all the answers

<p>Transactions do not release any locks until after they commit or abort. (B)</p> Signup and view all the answers

<p>To generate read_lock and write_lock requests. (B)</p> Signup and view all the answers

<p>Locking operations require memory allocation, maintenance, and complex algorithms that impact processing time. (D)</p> Signup and view all the answers

<p>Each transaction in a set is waiting for an item locked by another transaction in the same set. (D)</p> Signup and view all the answers

<p>Early Locking (B)</p> Signup and view all the answers

<p>It immediately aborts and restarts a transaction if it cannot obtain a lock. (C)</p> Signup and view all the answers

<p>To detect cycles indicating a deadlock situation. (D)</p> Signup and view all the answers

<p>Using a first-come-first-served queue. (D)</p> Signup and view all the answers

Set of rules designed to guarantee serializability in database transactions.

A protocol that locks data items to prevent concurrent access in two phases: growing and shrinking.

A variable associated with a data item that describes its status for operations that can be applied.

Locks with two states: locked (1) meaning inaccessible, and unlocked (0) meaning accessible.

A table that specifies which items currently have locks and their states.

Subsystem that keeps track of and controls access to locks in the database system.

Allows multiple transactions to read an item concurrently without conflict.

Requires exclusive control to write to an item, preventing other simultaneous writes.

Changing a lock held by a transaction from one type to another.

Switching from a read lock to a write lock in a transaction.

Switching from a write lock to a read lock in a transaction.

Phase where new locks can be acquired but not released.

Phase where existing locks can be released but no new ones can be acquired.

Standard Two-Phase Locking technique outlined earlier.

A version of 2PL that does not release locks until after a transaction commits or aborts.

A locking protocol where transactions do not release locks until they commit or abort.

A situation where two or more transactions are waiting for each other to release locks, leading to a standstill.

Methods to avoid deadlock by ensuring transactions lock all needed items in advance or in a specific order.

A deadlock prevention method where older transactions can wait for younger ones, but younger ones are aborted.

A deadlock prevention strategy where older transactions can 'wound' younger ones, forcing them to abort.

A strategy where if a transaction cannot obtain a lock, it is immediately aborted and later restarted.

A situation where a transaction cannot proceed for a long time while others continue to execute normally.

Deciding which transaction to abort when deadlock occurs, based on certain criteria or costs.

A unique identifier assigned by the DBMS for a transaction, indicating its start time.

Concurrency control techniques that utilize timestamps and avoid deadlocks since no locks are used.

A method allowing interleaved transaction operations while ensuring the order based on their timestamps.

An algorithm that rejects later conflicting operations by aborting the transaction that issued them, ensuring conflict serializability.

An extension of TO that guarantees schedules are both strict and conflict serializable.