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

-- 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;

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

Skill("postgresql-monitoring")