Database Deadlocks Explained: Causes, Detection, and Prevention
What a database deadlock is, why transactions lock each other out, how to detect deadlocks, and how to prevent them with lock ordering, timeouts, and retry.
Database Schema Migrations: Safe DDL Without Downtime
Why schema migrations cause outages, what makes a DDL change safe or unsafe, how to run zero-downtime migrations with expand-and-contract, and monitor them.
Database Failover and High Availability Explained
How database failover and high availability work — standby promotion, split-brain, quorum, automatic failover — and how to verify your HA actually recovers.
Database Replication Lag: Causes, Monitoring, and Fixes
What database replication lag is, why it happens, and how to monitor and reduce it so replicas don't serve stale data or break your reads during failover.
Database Connection Pool Exhaustion: Causes and Fixes
Why apps hit 'too many connections', how connection pool exhaustion happens, and how to diagnose, size, and fix it before it takes your database down.
ActiveRecord Monitoring: N+1, Slow Queries & Pool Exhaustion
Detect ActiveRecord N+1 queries, slow SQL and pool exhaustion in Rails. Bullet, Prosopite, pg slow logs, Sidekiq pool sizing, and HTTP latency as canary.
MySQL Production Monitoring: Slow Queries, Replication, Locks
Monitor MySQL in production. Performance Schema, slow query log, InnoDB buffer pool, replication lag, deadlocks, and alert thresholds.
PostgreSQL Production Monitoring: Slow Queries & Replication
Monitor PostgreSQL in production. pg_stat_statements, replication lag, autovacuum bloat, lock trees, connection pools, and alert thresholds.
Redis Production Monitoring: Memory, Eviction & Latency
Monitor Redis in production. INFO sections, maxmemory eviction, latency spikes, slowlog, replication, persistence, big keys, and cluster mode.
MongoDB Monitoring: Uptime, Replicas, and Clusters
MongoDB fails differently than SQL. Learn to monitor replica sets, sharded clusters, slow queries, and connection pools for production.
Database Monitoring Guide: MySQL, PostgreSQL & Redis
Database downtime brings your entire application down. Learn how to monitor MySQL, PostgreSQL, and Redis uptime, connectivity, and performance from outside.