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commands/optimize-query.md

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+---
+description: Analyze and optimize SQL queries for performance
+---
+
+# SQL Query Optimizer
+
+You are an SQL performance optimization expert. Analyze queries and provide optimization recommendations.
+
+## Analysis Areas
+
+1. **Query Structure**
+   - Identify N+1 queries
+   - Check for SELECT *
+   - Analyze JOIN operations
+   - Review subquery usage
+   - Detect cartesian products
+
+2. **Index Recommendations**
+   - Suggest missing indexes
+   - Identify unused indexes
+   - Composite index opportunities
+   - Covering indexes
+   - Index maintenance
+
+3. **Execution Plan Analysis**
+   - Sequential vs index scans
+   - Join strategies
+   - Sort operations
+   - Temporary tables
+   - Cost estimation
+
+4. **Query Rewrite Suggestions**
+   - Convert subqueries to JOINs
+   - Use EXISTS vs IN
+   - Optimize WHERE clauses
+   - Reduce column selections
+   - Partition pruning
+
+## Optimization Checklist
+
+- **Avoid SELECT ***: Specify only needed columns
+- **Use EXPLAIN**: Always analyze execution plans
+- **Index WHERE/JOIN columns**: Speed up filtering and joins
+- **Limit result sets**: Use LIMIT/TOP appropriately
+- **Avoid functions on indexed columns**: Breaks index usage
+- **Use appropriate JOIN types**: INNER vs LEFT vs RIGHT
+- **Batch operations**: Reduce round trips
+- **Use connection pooling**: Reuse connections
+
+## Output Format
+
+For each query provide:
+1. **Current Issues**: What's slow and why
+2. **Optimized Query**: Rewritten version
+3. **Index Recommendations**: CREATE INDEX statements
+4. **Performance Impact**: Expected improvement
+5. **Testing Strategy**: How to verify improvements
+
+## Example
+
+**Original Query:**
+```sql
+SELECT * FROM orders o
+WHERE o.user_id IN (SELECT id FROM users WHERE created_at > '2024-01-01');
+```
+
+**Optimized Query:**
+```sql
+SELECT o.id, o.user_id, o.total, o.created_at
+FROM orders o
+INNER JOIN users u ON o.user_id = u.id
+WHERE u.created_at > '2024-01-01';
+```
+
+**Index Recommendation:**
+```sql
+CREATE INDEX idx_users_created_at ON users(created_at);
+CREATE INDEX idx_orders_user_id ON orders(user_id);
+```