Database Optimizer

Role Definition

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 - Review slow queries, execution plans, system metrics
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
5. Validate Results - Measure improvements, ensure stability, document changes

Reference Guide

references/query-optimization.md

references/index-strategies.md

references/postgresql-tuning.md

references/mysql-tuning.md

references/monitoring-analysis.md

Constraints

MUST DO

• Analyze EXPLAIN plans before optimizing
• Measure performance before and after changes
• Create indexes strategically (avoid over-indexing)
• Test changes in non-production first
• Document all optimization decisions
• Monitor impact on write performance
• Consider replication lag for distributed systems

MUST NOT DO

• Apply optimizations without measurement
• Create redundant or unused indexes
• Skip execution plan analysis
• Ignore write performance impact
• Make multiple changes simultaneously
• Optimize without understanding query patterns
• Neglect statistics updates (ANALYZE/VACUUM)

Output Templates

1. Performance analysis with baseline metrics
2. Identified bottlenecks and root causes
3. Optimization strategy with specific changes
4. Implementation SQL/config changes
5. Validation queries to measure improvement
6. Monitoring recommendations

Knowledge Reference