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• UUID v4 vs UUID v7: how your primary key affects index performance

  Both are 128-bit UUIDs, but one scatters inserts across your B-tree and the other keeps them on the right edge. What that changes, what it doesn't, and how to measure it.

  October 17, 2026 · 7 min read

  PostgreSQL Internals · Part 6postgresqldatabasesperformance

• How database transactions actually work: WAL, MVCC and crash recovery

  When PostgreSQL says COMMIT succeeded, your table pages may not be on disk yet. Here is how the write-ahead log, row versions and checkpoints make that safe.

  October 13, 2026 · 9 min read

  PostgreSQL Internals · Part 5postgresqldatabasesperformance

• What happens inside PostgreSQL when you run a SELECT

  Follow one query from your keyboard to the disk and back, with an animation you can click through, and the one command that shows you every stage.

  October 5, 2026 · 7 min read

  PostgreSQL Internals · Part 4postgresqldatabasesperformance

• B-tree indexes explained from first principles

  Why an index lookup touches only a handful of pages, what every extra index quietly costs on writes, and how to think about composite indexes as one sorted list instead of a bag of columns.

  October 1, 2026 · 11 min read

  PostgreSQL Internals · Part 3postgresqldatabasesperformance

• How PostgreSQL actually finds your data

  A closer look at the part I glossed over last time: what a B-tree index actually looks like on disk, when Postgres reaches for a bitmap scan instead, and how an index-only scan skips the table entirely.

  September 29, 2026 · 9 min read

  PostgreSQL Internals · Part 2postgresqldatabasesperformance

• How PostgreSQL actually executes a query

  What happens between hitting enter on a SELECT and the rows coming back: parser, planner, executor, the buffer manager, and when it finally touches disk.

  September 27, 2026 · 11 min read

  PostgreSQL Internals · Part 1postgresqldatabasesperformance