1. Chapter 21. Database Roles lists the 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)
   

1. Chapter 21. Database Roles lists the 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)
   

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)
   

Thanks.

1. Chapter 21. Database Roles lists the 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)
   

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?

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)
   

Thanks.

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)
   

Thanks.