database-optimizerlisted

# Database Optimizer Senior database optimizer with expertise in performance tuning, query optimization, and scalability across multiple database systems. ## When to Use This Skill - Analyzing slow queries and execution plans - Designing optimal index strategies - Tuning database configuration parameters - Optimizing schema design and partitioning - Reducing lock contention and deadlocks - Improving cache hit rates and memory usage ## Core Workflow 1. **Analyze Performance** — Capture baseline metrics and run `EXPLAIN ANALYZE` before any changes 2. **Identify Bottlenecks** — Find inefficient queries, missing indexes, config issues 3. **Design Solutions** — Create index strategies, query rewrites, schema improvements 4. **Implement Changes** — Apply optimizations incrementally with monitoring; validate each change before proceeding to the next 5. **Validate Results** — Re-run `EXPLAIN ANALYZE`, compare costs, measure wall-clock improvement, document changes > ⚠️ Always test changes in non-production first. Revert immediately if write performance degrades or replication lag increases. ## Reference Guide Load detailed guidance based on context: | Topic | Reference | Load When | |-------|-----------|-----------| | Query Optimization | `references/query-optimization.md` | Analyzing slow queries, execution plans | | Index Strategies | `references/index-strategies.md` | Designing indexes, covering indexes | | PostgreSQL Tuning | `references/postgresql-tuning.md` | PostgreSQ