PostgreSQL Performance Optimization Guide

# PostgreSQL Performance Optimization Guide PostgreSQL is powerful, but getting the best performance requires understanding its internals. Here's my guide to optimization. ## Query Optimization ### EXPLAIN ANALYZE Always use EXPLAIN ANALYZE to understand query execution: ```sql EXPLAIN ANALYZE SELECT * FROM users WHERE email = 'test@example.com'; ``` ### Index Types - **B-tree**: Default, good for equality and range queries - **Hash**: Equality only, rarely better than B-tree - **GIN**: Full-text search, arrays, JSON - **GiST**: Geometric data, ranges ### Partial Indexes Index only the rows you need. ### Index-Only Scans Include all needed columns in the index to avoid table lookups. ## Configuration Tuning ### Memory Settings - shared_buffers: 25% of RAM - work_mem: Depends on concurrent queries - effective_cache_size: 50-75% of RAM ### Connection Pooling Use PgBouncer for connection management. ## Common Pitfalls 1. **N+1 queries**: Use JOINs or batch loading 2. **Missing indexes**: Index foreign keys 3. **Over-indexing**: Indexes slow down writes 4. **Not using VACUUM**: Keep statistics updated ## Monitoring ### pg_stat_statements Track query performance over time. ### Slow Query Log Log queries exceeding a threshold. ## Conclusion PostgreSQL optimization is iterative. Profile, optimize, measure, repeat.