What are the types of concurrency control methods?

What are the types of concurrency control methods in databases?

Concurrency control methods are techniques used to manage simultaneous operations on a database without conflicting. The main types include: 1. Pessimistic Concurrency Control 2. Optimistic Concurrency Control 3. Timestamp-based Concurrency Control 4. Multi-Version Concurrency Control (MVCC). Would you like to know more about any specific type?

Can you explain Pessimistic Concurrency Control?

Sure! Pessimistic Concurrency Control assumes that conflicts will occur. It locks the data when a transaction is being processed, preventing other transactions from accessing the same data until the lock is released. This ensures data integrity but can lead to reduced performance due to waiting.

What about Optimistic Concurrency Control?

Optimistic Concurrency Control, on the other hand, assumes that conflicts are rare. It allows transactions to proceed without locking the data. Before committing, it checks if any conflicts occurred. If a conflict is detected, the transaction is rolled back. This method can improve performance in low-conflict scenarios.

What are the advantages of using Multi-Version Concurrency Control?

Multi-Version Concurrency Control (MVCC) allows multiple versions of data to exist simultaneously. This means readers do not block writers and vice versa, improving performance and reducing wait times. It’s particularly useful in high-transaction environments.