remaining connection slots are reserved for non-replication superuser connections

使用客戶端工具鏈接pg，鏈接失敗，報錯如下錯誤：

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

查看數據庫鏈接狀態和配置信息

select * from pg_stat_activity where pid<>pg_backend_pid() and state='idle';##pg_backend_pid()的結果是當前會話的pid
select datname,datconnlimit from pg_database ;
select current_setting('max_connections');
select current_setting('superuser_reserved_connections');

　　

發現參數max_connections設置過低。

由於是測試環境，就先把idle狀態的鏈接先殺掉：

##把數據庫中的全部的空閒會話所有kill掉
select pg_terminate_backend(pid) from pg_stat_activity where pid<>pg_backend_pid() and state='idle';

 而後修改參數max_connections的值。