Articles

Leader-follower replication, lag, stale reads and split brain, measured on a real PostgreSQL primary and replica — including a three-second partition that cost 2,342 acknowledged writes, and what the manual actually guarantees instead.

ACID, the anomalies and MVCC, with six classic anomalies replayed at three isolation levels by two live PostgreSQL 18 sessions — including the one that leaves nobody on call at the level almost everyone runs.

Composite column order, covering indexes, why an index gets ignored and how to read EXPLAIN — measured on one PostgreSQL 18 table in pages touched, including three rules of thumb the measurements contradict.

Relational, document, key-value, wide-column, graph, time-series and search — chosen by the questions you ask, not the shape of your entities. One dataset, loaded three ways into PostgreSQL 18, with five access patterns measured in pages touched.

Pages, write-ahead logs, B-trees and LSM-trees, with write, read and space amplification measured on a page store and a miniature LSM, and PostgreSQL 18 measured on page layout, HOT updates, bloat and WAL bytes.

A cache from first principles: a map plus a recency list, TTLs without a timer per key, LRU against sampled and random eviction measured on a Zipf workload, and the stampede that takes your database down.

Designing a rate limiter from requirements to API: token bucket against fixed window with the boundary burst measured, an injected clock, thread safety, and what .NET, Java, Go and Rust’s libraries really do.

What layered, hexagonal and clean architecture really say, where they disagree, and how dependencies get inverted in C#, Java, Go and Rust, with .NET’s container lifetimes and captive dependencies shown in running code.

Strategy, adapter, decorator, middleware, observer, builder and state machines in C#, Java, Go and Rust, with the patterns each language feature deleted, and a measured look at what changes when you add a case.

Locks, atomics, channels, ownership and actors compared on one counter in C#, Java, Go and Rust, measured; what a data race really is, which bugs each model makes impossible, and which it quietly keeps.