Gülçin Yıldırım Jelinek – Anatomy of Table-Level Locks in PostgreSQL #bbuzz

Gülçin Yıldırım Jelinek explains how table-level locks and lock queuing work in PostgreSQL during DDL operations to avoid application downtime.

More: 2025.berlinbuzzwords.de/sessions/Anatomy-of-Table-Level-Lock… Speaker: Gülçin Yıldırım Jelinek This talks explains locking mechanisms (MVCC, lock queue) in PostgreSQL, focusing on table-level locks that are acquired by Data Definition Language(DDL) operations. If not managed well, schema changes can result in downtime. Not all operations require the same level of locking, and PostgreSQL offers tools and techniques to minimize locking impact. In PostgreSQL, managing schema changes without downtime can be a challenging task. Table-level locks, which control access during Data Definition Language (DDL) operations like ALTER or DROP TABLE, can result in unintended application slowdowns or even service interruptions when not fully understood. This talk will provide a comprehensive dive into table-level locking and lock queueing in PostgreSQL, helping attendees gain the insights they need to perform efficient schema changes. We’ll start by explaining the various types of table-level locks in PostgreSQL such as Access Share, Exclusive, and Access Exclusive and how they are automatically managed during common DDL operations. Then, we’ll break down lock queuing: how PostgreSQL organizes lock requests, what happens when transactions wait for locks, and how deadlocks can arise in complex environments. Next, we’ll focus on practical approaches to managing table-level locks for near-zero downtime. Attendees will learn techniques to minimize locking impact, including understanding lock conflicts, using online schema migration patterns, and identifying lock-heavy queries. We’ll introduce open-source tools like pgroll, which utilizes the expand/contract pattern to make schema changes in small, lock-free steps. By the end of this session, attendees will be equipped with practical strategies and knowledge to control lock behavior during schema changes, ensuring data integrity and reducing operational disruptions. This talk will provide the tools needed to manage PostgreSQL schema changes with confidence and minimal impact on production environments. ### Follow us on Social Media and join the Community! Mastodon: floss.social/@BerlinBuzzwords LinkedIn: linkedin.com/showcase/berlin-buzzwords Website: berlinbuzzwords.de Mail: info@berlinbuzzwords.de Berlin Buzzwords is an event by Plain Schwarz – plainschwarz.com