sql-pro

Iron Law

NEVER WRITE SQL WITHOUT KNOWING THE QUERY PLAN — USE EXPLAIN ANALYZE BEFORE CLAIMING A QUERY IS OPTIMIZED

When to Use This Skill

• Writing complex SQL queries or analytics (window functions, recursive CTEs, OLAP)
• Designing SQL for cloud-native platforms (BigQuery, Snowflake, Redshift, Aurora)
• Building HTAP or hybrid analytical/transactional systems
• Migrating from OLTP-only PostgreSQL to an analytics tier
• Dimensional modeling, data vault, star/snowflake schemas
• Integrating machine learning with SQL workloads
• Time-series analysis (TimescaleDB, InfluxDB, Apache Druid)

Do Not Use This Skill When

• You only need ORM-level guidance (use python-dev, nestjs-api, or java-spring-api)
• The system is non-SQL or document-only (use database-schema-designer for Firestore patterns)
• You need query optimization patterns for PostgreSQL OLTP (use sql-optimization-patterns)
• You cannot access query plans or schema details