remaining connection slots are reserved for non-replication superuser connections

使用客户端工具链接pg，链接失败，报错如下错误：

FATAL: remaining connection slots are reserved for non-replication superuser connections 

查看数据库链接状态和配置信息

select * from pg_stat_activity where pid<>pg_backend_pid() and state='idle';##pg_backend_pid()的结果是当前会话的pid
select datname,datconnlimit from pg_database ;
select current_setting('max_connections');
select current_setting('superuser_reserved_connections');

　　

发现参数max_connections设置过低。

由于是测试环境，就先把idle状态的链接先杀掉：

##把数据库中的全部的空闲会话所有kill掉
select pg_terminate_backend(pid) from pg_stat_activity where pid<>pg_backend_pid() and state='idle';

 而后修改参数max_connections的值。