remaining connection slots are reserved for non-replication superuser connections

使用客戶端工具連接pg，連接失敗，報錯以下錯誤：

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

查看數據庫連接狀態和配置信息

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設置太低。

因為是測試環境，就先把idle狀態的連接先殺掉：

##把數據庫中的所有的空閑會話全部kill掉
select pg_terminate_backend(pid) from pg_stat_activity where pid<>pg_backend_pid() and state='idle';

 然后修改參數max_connections的值。