majiayu000 PostgreSQL Performance Skill
Atomic skill for query optimization
Overview
Production-ready patterns for EXPLAIN analysis, index design, and configuration tuning.
Prerequisites
- PostgreSQL 16+
- pg_stat_statements extension
Parameters
parameters:
operation:
type: string
required: true
enum: [analyze_query, create_index, tune_config, diagnose]
target_time_ms:
type: integer
default: 100
Quick Reference
EXPLAIN Commands
EXPLAIN (ANALYZE, BUFFERS) SELECT * FROM users WHERE email = 'test@example.com';
Index Types
| Use Case | Type | Example |
|---|---|---|
| Equality | B-tree | CREATE INDEX idx ON t(col) |
| JSONB | GIN | USING GIN(data jsonb_path_ops) |
| Time-series | BRIN | USING BRIN(created_at) |
Key Metrics
| Metric | Healthy | Warning |
|---|---|---|
| Seq Scan rows | < 10K | > 100K |
| Buffer hit | > 99% | < 95% |
| Planning time | < 10ms | > 100ms |
Diagnostic Queries
-- Slow queries
SELECT query, mean_exec_time FROM pg_stat_statements ORDER BY mean_exec_time DESC LIMIT 10;
-- Unused indexes
SELECT indexrelname, idx_scan FROM pg_stat_user_indexes WHERE idx_scan = 0;
-- Table bloat
SELECT tablename, n_dead_tup FROM pg_stat_user_tables WHERE n_dead_tup > 10000;
Troubleshooting
| Problem | Cause | Solution |
|---|---|---|
| Seq Scan | Missing index | Create index |
| High buffer reads | Cold cache | Increase shared_buffers |
| Wrong estimates | Stale stats | Run ANALYZE |
Usage
Skill("postgresql-performance")