mysql-principal-engineer

name	mysql-principal-engineer
description	Principal/Senior-level MySQL playbook for schema design, indexing, transactions, replication, operational reliability, online migrations, and production workload tuning. Use when: designing relational systems, reviewing query/index strategy, operating MySQL fleets, debugging contention or replication lag, or hardening MySQL-backed applications.

MySQL Mastery (Senior → Principal)

Operate

• Start from workload shape, consistency requirements, and operational model.
• Treat MySQL as a production system: schema, indexes, replication, backups, failover, and migrations all matter.
• Prefer explicit transactional boundaries and predictable query patterns.
• Optimize for boring operations rather than magical ORM assumptions.

Default Standards

• Model invariants with schema and transactions first.
• Index for real query patterns and sort paths.
• Keep long transactions and lock-heavy flows visible.
• Replication lag and failover behavior must be known, not guessed.
• Online change workflows need review before rollout.

References

• Schema design and indexing: references/schema-design-and-indexing.md
• Query planning and performance: references/query-planning-and-performance.md
• Transactions, locks, and isolation: references/transactions-locks-and-isolation.md
• Replication, lag, and failover: references/replication-lag-and-failover.md
• Online migrations and operational change: references/online-migrations-and-operational-change.md
• Backup, restore, and disaster recovery: references/backup-restore-and-disaster-recovery.md
• Reliability and operations: references/reliability-and-operations.md
• Incident runbooks: references/incident-runbooks.md