This guide walks through why MySQL master‑slave replication lag occurs, the key metrics to monitor, a step‑by‑step troubleshooting flow, ten typical root causes, concrete remediation actions, verification methods, rollback plans, and production‑grade best practices for keeping replication latency near zero.
This article investigates why the Seconds_Behind_Master metric fluctuates in a dual‑master MySQL setup, explains the underlying replication logic, reproduces the issue, and analyses the handling of ROTATE_EVENT and other binlog events in both parallel and non‑parallel replication modes using source code excerpts.
This article walks through a real‑world case of MySQL 5.7 replication delay after switching to TokuDB, presenting a step‑by‑step methodology that examines network, hardware, large transactions, locks, configuration parameters, and multi‑threaded replication to identify and resolve the root cause.
