Kubai Kevin

Redis vs Valkey vs Dragonfly: which in-memory store?

A mechanism-first guide to picking Redis, Valkey or Dragonfly: fork history, single-thread limits, expiry semantics, migration tests and metrics.

17 min read · 7 November 2026

Database restore drills that mean something

A repeatable PostgreSQL restore drill that measures recovery time, data loss window and integrity, plus the failure modes that make drills lie.

15 min read · 28 October 2026

Read replicas: the bug factory you built

Read replicas lag by design. Learn how to classify reads, route freshness-critical queries to the primary, and measure your exposure to stale reads.

15 min read · 18 October 2026

Memory Systems for Production Agents

How in-memory stores, caches, and stateful services leak context in production agents, plus code, failure modes, and instrumentation to measure it yourself.

11 min read · 15 September 2026

When a vector DB misconfiguration breaks RAG silently

Vector DB misconfigurations cause RAG outages that look like app bugs. Learn to detect index errors, add circuit breakers, and instrument query latency.

11 min read · 29 July 2026

Postgres vector search: what breaks first

pgvector works until load grows. Here is what fails first, how to measure it, and when a dedicated ANN service earns its operational cost.

13 min read · 24 July 2026

Stop the writes — zero-downtime DB migrations

Zero-downtime migrations fail when writes keep flowing during the copy. A drain-copy-flip state machine, with instrumentation and a decision checklist.

13 min read · 2 July 2026

Postgres 17 swallowed Redis, Kafka, Timescale

How to evaluate consolidating Redis, Kafka and a time-series database into Postgres extensions, with honest limits, failure modes and a checklist.

14 min read · 2 July 2026

RAG on legacy systems: vector DB vs. full-text SQL

Compare vector databases and in-database vector search for adding RAG to legacy systems, with latency, cost, and operational trade-offs.

14 min read · 30 June 2026

Migrations? Stop running them live

Why live schema migrations cause outages, and how versioning the schema as a deployable artifact with expand/contract steps reduces that risk.

11 min read · 28 June 2026

Log audit costs without breaking compliance

Compare PostgreSQL and ClickHouse for audit logging: write amplification, query latency, retention, cost modelling, and a decision checklist.

13 min read · 22 June 2026

Neon vs PlanetScale vs Turso: which broke first?

Diagnose connection drops, replica lag and proxy limits in Neon, PlanetScale and Turso, with reproducible tests and fixes that do not rely on guesswork.

13 min read · 10 June 2026

Soft deletes fail: what breaks first

Soft deletes leak into every query and bloat indexes. Here is how to measure the damage and move to a tiered live/archive/cold lifecycle.

13 min read · 9 June 2026

RAG pipelines: 4 silent prod killers

A practical guide to the silent failure modes that break RAG pipelines at scale: tokenizer drift, GPU fragmentation, index skew, and cache stampedes.

13 min read · 8 June 2026