# PostgreSQL internals, explained simply

One mechanism per post, in the order a change flows through the server. Analogy first, then the real thing, then the gotchas.

> Canonical URL: https://sudohulk.com/tracks/pg-internals-simply
> Kind: series
> Status: active
> Started: 2026-10-17
> Progress: 1/5 parts (20%)
> Last activity: 2026-10-17
> Feed: https://sudohulk.com/tracks/pg-internals-simply/rss.xml
> Tags: postgresql, databases
> Author: Vignesh Kumar A <vignesh@sudohulk.com>
> Licence: CC BY 4.0. Quote freely, cite the canonical URL.

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## Parts

- [ ] WAL, explained simply
- [ ] What actually happens between BEGIN and COMMIT
- [ ] Checkpoints and the redo point
- [ ] Two-phase commit in vanilla PostgreSQL
- [x] How PostgreSQL tells every connection its cache is stale, done 2026-10-17 ([How PostgreSQL tells every connection its cache is stale](https://sudohulk.com/writing/postgres-cache-invalidation))