PostgreSQL 报错及其解决办法：FATAL: remaining connection slots are reserved for non-replication superuser connections
报错描述：FATAL: remaining connection slots are reserved for non-replication superuser connections
原因：普通用户的连接已满，保留用于非复制的超级用户连接。由于连接已满，可以关闭空闲的连接
解决办法：
1）查询当前所有连接的状态
select datname,pid,application_name,state from pg_stat_activity;
2）关闭当前state为 idle 空闲状态的连接
查看数据库剩余连接数：
select max_conn-now_conn as resi_conn from (select setting::int8 as max_conn,(select count(*) from pg_stat_activity) as now_conn from pg_settings where name = ‘max_connections’) t;
查看为超级用户保留的连接数:
show superuser_reserved_connections;
psql: FATAL: 53300: sorry, too many clients already
数据库连接已满，无法建立新的连接。
1、关闭空闲连接
select datname,pid,application_name,state from pg_stat_activity;
–查看目前所有的连接的进程id、应用名称、状态。
select pg_terminate_backend(pid) from pg_stat_activity;
–通过pid终止空闲连接
当前总共正在使用的连接数：
select count(1) from pg_stat_activity;
显示系统允许的最大连接数
show max_connections;
显示系统保留的用户数
show superuser_reserved_connections ;