Troubleshoot Proxysql

When to use this skill

Backend Connection Starvation: Backend pool saturates. New queries queue or timeout.
Multiplexing Collapse: Too many pinned sessions. Approaches 1:1 client-to-backend ratio.
Monitor False Decisions: Health checks misconfigured. Backends flap between ONLINE and SHUNNED.
Query Rule CPU Overload: Complex regex in mysql_query_rules saturates worker threads.
Configuration Drift: Changes not propagated between RUNTIME/MEMORY/DISK layers.
Cache Stampede: Hot cache entry expires, thundering herd hits backend.
Any time the user reports a Proxysql service behaving outside its expected envelope (elevated errors, latency, saturation, resource exhaustion, or unexpected restarts).
An on-call engineer is paging on a Netdata alert tied to a Proxysql instance and wants a structured triage path.