Database: Optimistic vs. Pessimistic Locking

Detail the tradeoffs between optimistic concurrency control (OCC) and pessimistic locking in high-throughput databases.

Technical Reference & Key Concepts

The Challenge: Concurrency Control

Your application experiences race conditions during high-concurrency balance updates. You must choose between Optimistic (OCC) and Pessimistic locking.

Core questions to address:

  1. In what scenario is Optimistic Locking (OCC) preferred over Pessimistic Locking?
  2. What is the operational cost of transaction retries under high contention in OCC?
  3. How do you implement Pessimistic locking in SQL (e.g., using Postgres)?