Podcast
Questions and Answers
Which ACID property ensures that a transaction will remain unchanged even in case of a system failure?
Which ACID property ensures that a transaction will remain unchanged even in case of a system failure?
- Consistency
- Isolation
- Durability (correct)
- Atomicity
What is a key benefit of using lock-based protocols in concurrency control?
What is a key benefit of using lock-based protocols in concurrency control?
- They prevent deadlocks entirely.
- They do not require a locking hierarchy.
- They operate without timestamps.
- They ensure conflict serializability. (correct)
Which method is used to recover from a system crash in advanced recovery systems?
Which method is used to recover from a system crash in advanced recovery systems?
- View serializability
- Deadlock detection
- Checkpointing (correct)
- Locking
What is a characteristic feature of B+ trees as a dynamic index structure?
What is a characteristic feature of B+ trees as a dynamic index structure?
In timestamp-based protocols, what does the timestamp of a transaction represent?
In timestamp-based protocols, what does the timestamp of a transaction represent?
Flashcards
Concurrency Control
Concurrency Control
Methods used to manage multiple transactions executing simultaneously without inconsistencies.
ACID Properties
ACID Properties
Atomicity, Consistency, Isolation, Durability – guarantees reliable database transactions.
Index Data Structures
Index Data Structures
Organize data in databases for fast retrieval using keys.
B+ Trees
B+ Trees
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ARIES
ARIES
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Study Notes
ACID Properties
- ACID properties ensure data integrity during concurrent transactions.
Concurrent Executions
- Conflict serializability: A schedule of concurrent transactions is conflict serializable if it can be transformed into a serial schedule by swapping transactions that do not conflict.
- View serializability: A schedule of concurrent transactions is view serializable if each transaction's view of the data is the same as if the transactions were executed serially.
Concurrency Control
- Lock-based protocols: Use locks to control access to data items, preventing conflicts during concurrent transactions.
- Deadlock handling: Techniques like deadlock detection and deadlock prevention are used to identify and resolve cyclic dependencies between transactions.
- Timestamp-based protocols: Assign timestamps to transactions and use them to resolve conflicts.
- Multiple granularity: Allows locking at different levels (e.g., table, page, row) providing flexibility in concurrency control strategies.
Advanced Recovery Systems
- ARIES (Adaptive Logging): An advanced logging protocol for database recovery.
- Log: A crucial component for recording all changes made to the database.
- Write-ahead log protocol: Ensures that log records are written to disk before changes are made to the database, allowing recovery mechanisms to restore the database to a consistent state.
- Checkpointing: Periodically saving the current state of the database to disk, speeding up recovery in the event of a system crash.
- Recovering from a system crash: Procedures to restore the database to a consistent state after a crash using log information.
Primary and Secondary Indexes
- Index data structures: Specialized data structures used to speed up data retrieval.
- Hash-based indexing: Based on hash functions to map data values to index entries.
- Tree-based indexing: Hierarchical structures like B+ trees.
- B+ Trees: A dynamic index structure supporting efficient searching, insertion, and deletion of data.
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