parameters:
  operation:
    type: string
    required: true
    enum: [collect_metrics, setup_alerting, diagnose]
  metric_type:
    type: string
    enum: [connections, queries, replication, storage]

Quick Reference

Key Queries

-- Connection stats
SELECT count(*), state FROM pg_stat_activity GROUP BY state;

-- Slow queries
SELECT query, mean_exec_time FROM pg_stat_statements
ORDER BY mean_exec_time DESC LIMIT 10;

-- Cache hit ratio
SELECT round(100.0 * sum(heap_blks_hit) /
    nullif(sum(heap_blks_hit + heap_blks_read), 0), 2) as ratio
FROM pg_statio_user_tables;

-- Table sizes
SELECT tablename, pg_size_pretty(pg_total_relation_size(tablename::regclass))
FROM pg_tables WHERE schemaname = 'public' ORDER BY pg_total_relation_size(tablename::regclass) DESC;

-- Replication lag
SELECT client_addr, pg_size_pretty(pg_wal_lsn_diff(sent_lsn, replay_lsn)) as lag
FROM pg_stat_replication;

Critical Thresholds

Metric	Warning	Critical
Connections	80% max	95% max
Cache hit	< 99%	< 95%
Replication lag	> 1MB	> 100MB
Dead tuples	> 10K	> 100K

Prometheus Exporter

postgres-exporter:
  image: prometheuscommunity/postgres-exporter
  environment:
    DATA_SOURCE_NAME: "postgresql://monitor:pass@postgres:5432/postgres"

Troubleshooting

Problem	Cause	Solution
No stats	Extension missing	CREATE EXTENSION pg_stat_statements
Old metrics	Stats not reset	pg_stat_statements_reset()
High connections	Leak or surge	Check application

Usage

Skill("postgresql-monitoring")

postgresql-monitoring

PostgreSQL Monitoring Skill

Overview

Prerequisites

Parameters