What problem does it solve? Designing and troubleshooting MySQL or MariaDB databases involves subtle decisions around indexing, transactions, connection pools, and replication where mistakes cause slow queries, deadlocks, and stale reads. This Skill provides evidence-backed review guidance for schema design, slow-query investigation, and production configuration without requiring direct database access. ## Core Features & Use Cases - Schema and Index Review: Apply defaults for primary keys, utf8mb4 text, DECIMAL money columns, soft deletes, and composite index ordering, then validate against caller-supplied EXPLAIN plans. - Query and Transaction Patterns: Implement upserts with MySQL/MariaDB-compatible syntax, keyset pagination, JSON generated columns, full-text search, and deadlock-safe transaction ordering with SKIP LOCKED queue claims. - Operations Guidance: Review connection pool settings (SQLAlchemy, mysql2), replication lag risks, least-privilege grants, and InnoDB configuration values as review prompts rather than presets. - Use Case: A developer investigating a slow orders endpoint supplies an EXPLAIN plan and table definition; the Skill identifies a missing composite index on (account_id, status, created_at) and returns the exact CREATE INDEX statement plus a validation plan. ## Quick Start Ask the assistant to review your MySQL table schema, slow query, or migration plan using the ecc-mysql-patterns guidance and paste the relevant SQL or EXPLAIN output.
