postgres是PostgreSQL的默认默认用户吗？

1. https：// www。 postgresql.org/docs/10/static/default-roles.html 列出了
   个Postgresql的默认角色。但是我找不到用户 postgres ，
   是在postgresql中默认创建的。 postgres 是
   的默认角色吗？手册会丢失还是误解？


2. 在postgresql中， postgres 是特殊用户，还是普通用户仅
   像手动创建的一样？ PostgreSQL服务器是否需要用户 postgres ？要删除它会给服务器或其他问题造成麻烦吗？



3. 以下两个在psql中运行的命令提供了默认角色或
   用户名，都包括 postgres 。

1. https://www.postgresql.org/docs/10/static/default-roles.html lists default roles of postgresql. But I don't find user postgres there, which has been created by default in postgresql. Is postgres a default role? Does the manual miss it or do I misunderstand?
2. In postgresql, is postgres a special user, or a regular user just like one created manually? Does the PostgreSQL server need the user postgres? WIll removing it cause some trouble to the server or something else?

3. The following two commands run in psql provide default roles or usernames, which both include postgres. why do they differ?

# select usename from pg_catalog.pg_user;
 usename  
----------
 postgres
(1 row)

# select rolname from pg_catalog.pg_roles;
       rolname        
----------------------
 postgres
 pg_monitor
 pg_read_all_settings
 pg_read_all_stats
 pg_stat_scan_tables
 pg_signal_backend
(6 rows)

谢谢。