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.
PostgreSQL UUID Primary Key Performance: Debugging Index Bloat and Insert Slowdowns
A direct guide to diagnosing and fixing UUID primary key performance problems in PostgreSQL—index bloat, random writes, and cache thrashing.
Postgres Advisory Lock Not Releasing: A Debugging Guide
Practical debugging guide for PostgreSQL advisory locks that won't release. Covers session management, connection pooling, transaction scoping, and stuck backends.
Debugging MySQL Replication Lag: From Seconds to Hours
A practical guide to diagnosing and fixing MySQL replication lag that spikes from seconds to hours, covering both obvious and subtle causes.
MySQL Index Merge Causing Slow Queries: How to Detect and Fix
Diagnose and fix slow queries caused by MySQL index merge. Learn to identify when index_merge is harmful and how to force single-index scans.
MySQL utf8mb4 Encoding Error When Storing Emoji
A step-by-step guide to diagnosing and fixing MySQL utf8mb4 encoding errors that prevent storing emoji characters in your database.
MySQL Lock Wait Timeout Exceeded: A Practical Debugging Guide
A hands-on guide to diagnosing and fixing MySQL 'Lock wait timeout exceeded' errors, covering real-world cases, transaction isolation traps, and deadlock prevention.
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.