Buglyst Blog
Learn to debug under pressure.
Playbooks for fast pattern recognition, guides for the full investigation, and articles for the engineering judgment around the edges.
17 playbooks · 509 guides · 95 articles · 12 linked practice labs ·skip to practice
Fast pattern recognition for the production failures engineers see most often.
3 playbooks in Data & Storage
Debugging Pagination Bugs
Pagination bugs hide in boundary math, cursor reuse, and new records arriving between pages.
Debugging Transaction Rollback Issues
How to find partial writes when multi-step database workflows fail mid-request.
Debugging Database Consistency Bugs
How to trace query consistency issues across repositories, replicas, and API response contracts.
Structured investigations for the failure modes engineers meet in real systems.
Chasing Down the N+1 Query Problem in Production APIs
How to identify, analyze, and fix the N+1 query bug in backend APIs. Real commands, logs, and war stories from production-grade systems.
Analyzing and Debugging Slow Queries in Postgres
Diagnosing and resolving slow queries in PostgreSQL demands a systematic approach. This guide covers concrete steps, tools, and gotchas for real-world cases.
Debugging PostgreSQL Deadlocks: From Detection to Fix
A practical guide to identifying, diagnosing, and resolving PostgreSQL deadlocks with real-world examples and specific commands.
Postgres Index Not Being Used by Query Planner
A practical guide to diagnosing why PostgreSQL's query planner ignores an index and how to force it when appropriate.
Row Lock Contention with SELECT FOR UPDATE in PostgreSQL
A deep guide to diagnosing and fixing row lock contention caused by SELECT FOR UPDATE queries in PostgreSQL, including queue buildup, deadlocks, and performance degradation.
PostgreSQL Connection Pool Exhaustion: Debugging When All Connections Are Taken
A practical guide to diagnosing and fixing Postgres connection pool exhaustion with real-world commands and patterns.
Long-form thinking on debugging habits, observability, and the systems around the bug.
How Database Indexes Work: A Debugging Story
A practical guide to understanding database indexes through the lens of debugging a real production outage caused by a missing covering index.
Reading PostgreSQL EXPLAIN ANALYZE Output: A Practical Guide with Real Query Examples
EXPLAIN ANALYZE is the single most important tool for diagnosing slow queries. Here's how to read the output, spot common pitfalls, and fix them with real-world examples.
Debugging Cache Invalidation Failures: A Case Study with Redis and PostgreSQL
Cache invalidation sounds simple — write-through, TTLs, done. But in practice, silent failures hide in race conditions, connection pools, and stale read replicas. Here's a real debugging story with Redis and PostgreSQL that taught me how to find them.
The Real Cost of N+1 Queries: More Than Just Slow Pages
N+1 queries are often dismissed as a minor performance issue, but their real cost goes far beyond slow page loads—think cascading timeouts, database meltdowns, and cloud bills that balloon overnight. Here's what you're actually paying for.