Postgres schema migrations using the expand/contract pattern
summary
Shows how the expand/contract pattern performs zero‑downtime Postgres migrations by keeping old and new schema live simultaneously, using pgroll to automate the two‑phase start/complete flow. Migrations are expressed as JSON, pgroll creates per‑version schema views and installs triggers for dual‑write so application V1 and V2 see different projections of the same table while a batched backfill runs. Tool is Postgres‑specific, open source (Apache), aims to avoid long exclusive locks and make rollbacks safer by removing added objects during contract.
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chapters (8)
- 0:00Introduction and context
- 4:30Common migration pitfalls
- 11:13Tools and techniques
- 14:22Expand contract pattern
- 21:41Introducing pgroll
- 25:19Demonstration
- 35:33Lessons and takeaways
- 38:00Q&A
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