PostgreSQl-数据库连接数

-- 最大连接数
show max_connections;

-- 占用连接数
SELECT COUNT(*) FROM pg_stat_activity;

-- 各个数据库占用的连接数

SELECT a.datname, COUNT(*) 
FROM pg_stat_activity as a
JOIN pg_database as b ON a.datname = b.datname 
GROUP BY a.datname;

-- 按IP分组查看占用数
SELECT  client_addr,count(*)
FROM pg_stat_activity group by client_addr