This article explains five counterintuitive PostgreSQL locking behaviors that can cause unexpected performance issues and outages. It covers scenarios like ALTER TABLE operations getting blocked by long-running SELECT queries and creating chain reactions of blocked queries. The content provides practical examples and explanations that are valuable for database administrators and developers working with PostgreSQL in production environments.
Background
PostgreSQL uses MVCC (Multi-Version Concurrency Control) for concurrency control, with 8 table-level lock modes and 4 row-level lock modes. While the locking system is well-documented, real-world usage often reveals unexpected locking conflicts that can lead to performance degradation and system outages.
- Source
- Lobsters
- Published
- May 27, 2026 at 06:04 PM
- Score
- 7.0 / 10