Labs · MySQL

Practice real MySQL scenarios before they happen

Practice the MySQL failures that page on-call — full scans, connection pressure, InnoDB locks, broken replication and unsafe failovers — against a real MySQL sandbox.

Start now → Explore scenarios

Run rillence mysql · real MySQL in Docker · deterministic scoring.

What it is

A flight simulator for MySQL operations

Boot a real MySQL in a container, inject a realistic failure, and investigate with the mysql client or your own tooling. Deterministic scoring, zero production risk.

Real MySQL sandbox

Every scenario runs an actual MySQL instance in a container — not a multiple-choice quiz or a video.

Real scenarios

Full table scans, connection storms, InnoDB deadlocks, replication breaks and blocking migrations — injected into a live instance.

AI hints + deterministic scoring

Get progressive hints while you investigate, a scorecard for your fix and a postmortem explaining the root cause.

Built for individuals and teams

Practice alone, onboard new engineers, or run repeatable internal MySQL team drills.

Scenarios

MySQL scenarios, grouped into tracks

The MySQL failure modes engineers actually meet in production — from EXPLAIN to InnoDB, replication and failover.

Query Performance & Indexing

Core

Missing composite indexes, wrong column order, covering indexes and full table scans.

Connections, Threads & ProxySQL

Core

Too many connections, connection leaks, thread pressure and ProxySQL routing.

InnoDB Locks, Transactions & Isolation

Core

Deadlocks, lock waits, gap locks, long transactions and isolation surprises.

Replication & Binlog

Operations

Replica lag, broken binlog, GTID gaps and replication that silently stops.

Backup, Restore & PITR

Operations

Bad backups, slow restores, point-in-time recovery and binlog gaps.

Multi-Schema & Tenant Operations

Operations

Schema drift, per-tenant load, noisy neighbours and cross-schema queries.

InnoDB Undo, Purge & Maintenance

Operations

Undo bloat, purge lag, history-list growth and maintenance stalls.

HA & Failover

Advanced

Failover that drops writes, split-brain, stale replicas and VIP routing.

Migrations & Releases

Advanced

Blocking ALTERs, online schema changes and unsafe release steps.

Security & Access

Advanced

Grants gone wrong, exposed accounts, auth failures and access scoping.

Compound MySQL Incidents

Capstone

Multi-cause GameDays combining locks, replication and connection pressure.

Incident Control

Capstone

Incident-commander scenarios coordinating diagnosis and fix under pressure.

How practice works

From paged to postmortem in four steps

Launch the lab

Run rillence mysql to open the interactive REPL.

Start a scenario

Pick a scenario from any track and boot an isolated MySQL sandbox.

Investigate

Connect with the mysql client — or any client you already use — and dig in.

Submit and score

Get deterministic Detect / Fix / Trap scoring and a postmortem.

Practice MySQL scenarios before they become outages

One subscription covers every lab. Train your judgment in a safe sandbox, not in production.

Start now → All labs