--- title: The Postgres migration that locks your table at 3am, and... description: A deep dive into 10 PostgreSQL migration patterns that cause table locks and production outages, with safe rewrites for each. Covers dangerous operations like... canonical: https://daily.dev/posts/the-postgres-migration-that-locks-your-table-at-3am-and-how-to-catch-it-in-review-19nuvuqqn twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: The Postgres migration that locks your table at 3am, and how to catch it in review | daily.dev og:description: A deep dive into 10 PostgreSQL migration patterns that cause table locks and production outages, with safe rewrites for each. Covers dangerous operations like... og:url: https://daily.dev/posts/the-postgres-migration-that-locks-your-table-at-3am-and-how-to-catch-it-in-review-19nuvuqqn og:image: https://api.daily.dev/og/posts/19NUVUqqN.png og:image:alt: The Postgres migration that locks your table at 3am, and how to catch it in review og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # The Postgres migration that locks your table at 3am, and how to catch it in review **[Medium](https://daily.dev/sources/medium_js)** · 6 min read · 0 upvotes · 0 comments ## Summary A deep dive into 10 PostgreSQL migration patterns that cause table locks and production outages, with safe rewrites for each. Covers dangerous operations like CREATE INDEX without CONCURRENTLY, direct SET NOT NULL, ADD FOREIGN KEY without NOT VALID, ADD COLUMN with volatile defaults, and ALTER COLUMN TYPE. The core pattern: never hold a strong ACCESS EXCLUSIVE lock while scanning or rewriting a large table — split dangerous one-step changes into fast metadata changes plus separately-locked scans or batched backfills. Also covers lock_timeout best practices and destructive operations. The author promotes a paid migration auditing tool (EUR 14.99) and a free open-source CLI/GitHub Action alternative. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Zero-Downtime Postgres Migrations: A 2026 Developer Guide](https://daily.dev/posts/zero-downtime-postgres-migrations-a-2026-developer-guide-drbnzykbh) · Alex CloudStar · 0 upvotes · 0 comments - [Hatchet](https://daily.dev/posts/hatchet-9ijgag52h) · Hacker News · 0 upvotes · 0 comments - [Troubleshooting row lock contention in Amazon Aurora PostgreSQL: Part 1 – Understanding row lock contention in PostgreSQL](https://daily.dev/posts/troubleshooting-row-lock-contention-in-amazon-aurora-postgresql-part-1-understanding-row-lock-con-pjjvnrtvx) · AWS Database Blog · 0 upvotes · 0 comments - [Row locks at the page level](https://daily.dev/posts/row-locks-at-the-page-level-o9spsmh7b) · Planet PostgreSQL · 0 upvotes · 0 comments --- Tags: [#database](https://daily.dev/tags/database), [#postgresql](https://daily.dev/tags/postgresql) [View this post on daily.dev](https://daily.dev/posts/the-postgres-migration-that-locks-your-table-at-3am-and-how-to-catch-it-in-review-19nuvuqqn) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"The Postgres migration that locks your table at 3am, and how to catch it in review","url":"https://daily.dev/posts/the-postgres-migration-that-locks-your-table-at-3am-and-how-to-catch-it-in-review-19nuvuqqn","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/the-postgres-migration-that-locks-your-table-at-3am-and-how-to-catch-it-in-review-19nuvuqqn"},"datePublished":"2026-07-26T07:33:17.270Z","dateModified":"2026-07-26T07:39:47.972Z","description":"A deep dive into 10 PostgreSQL migration patterns that cause table locks and production outages, with safe rewrites for each. 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