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$PostgreSQL: pgsql/doc/src/sgml/ref/create_role.sgml,v 1.14 2010/04/03 07:22:58 petere Exp $
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<refentry id="SQL-CREATEROLE">
 <refmeta>
  <refentrytitle>CREATE ROLE</refentrytitle>
  <manvolnum>7</manvolnum>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>CREATE ROLE</refname>
  <refpurpose>define a new database role</refpurpose>
 </refnamediv>

 <indexterm zone="sql-createrole">
  <primary>CREATE ROLE</primary>
 </indexterm>

 <refsynopsisdiv>
<synopsis>
CREATE ROLE <replaceable class="PARAMETER">name</replaceable> [ [ WITH ] <replaceable class="PARAMETER">option</replaceable> [ ... ] ]

<phrase>where <replaceable class="PARAMETER">option</replaceable> can be:</phrase>
    
      SUPERUSER | NOSUPERUSER
    | CREATEDB | NOCREATEDB
    | CREATEROLE | NOCREATEROLE
    | CREATEUSER | NOCREATEUSER
    | INHERIT | NOINHERIT
    | LOGIN | NOLOGIN
    | CONNECTION LIMIT <replaceable class="PARAMETER">connlimit</replaceable>
    | [ ENCRYPTED | UNENCRYPTED ] PASSWORD '<replaceable class="PARAMETER">password</replaceable>'
    | VALID UNTIL '<replaceable class="PARAMETER">timestamp</replaceable>' 
    | IN ROLE <replaceable class="PARAMETER">role_name</replaceable> [, ...]
    | IN GROUP <replaceable class="PARAMETER">role_name</replaceable> [, ...]
    | ROLE <replaceable class="PARAMETER">role_name</replaceable> [, ...]
    | ADMIN <replaceable class="PARAMETER">role_name</replaceable> [, ...]
    | USER <replaceable class="PARAMETER">role_name</replaceable> [, ...]
    | SYSID <replaceable class="PARAMETER">uid</replaceable> 
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <command>CREATE ROLE</command> adds a new role to a
   <productname>PostgreSQL</productname> database cluster.  A role is
   an entity that can own database objects and have database privileges;
   a role can be considered a <quote>user</>, a <quote>group</>, or both
   depending on how it is used.  Refer to
   <xref linkend="user-manag"> and <xref
   linkend="client-authentication"> for information about managing
   users and authentication.  You must have <literal>CREATEROLE</>
   privilege or be a database superuser to use this command.
  </para>

  <para>
   Note that roles are defined at the database cluster
   level, and so are valid in all databases in the cluster.
  </para>
 </refsect1>

 <refsect1>
  <title>Parameters</title>

    <variablelist>
     <varlistentry>
      <term><replaceable class="parameter">name</replaceable></term>
      <listitem>
       <para>
        The name of the new role.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><literal>SUPERUSER</literal></term>
      <term><literal>NOSUPERUSER</literal></term>
      <listitem>
       <para>
        These clauses determine whether the new role is a <quote>superuser</>,
        who can override all access restrictions within the database.
        Superuser status is dangerous and should be used only when really
        needed.  You must yourself be a superuser to create a new superuser.
        If not specified,
        <literal>NOSUPERUSER</literal> is the default.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><literal>CREATEDB</></term>
      <term><literal>NOCREATEDB</></term>
      <listitem>
       <para>
        These clauses define a role's ability to create databases.  If
        <literal>CREATEDB</literal> is specified, the role being
        defined will be allowed to create new databases. Specifying
        <literal>NOCREATEDB</literal> will deny a role the ability to
        create databases. If not specified,
        <literal>NOCREATEDB</literal> is the default.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><literal>CREATEROLE</literal></term>
      <term><literal>NOCREATEROLE</literal></term>
      <listitem>
       <para>
        These clauses determine whether a role will be permitted to
        create new roles (that is, execute <command>CREATE ROLE</command>).
        A role with <literal>CREATEROLE</literal> privilege can also alter
        and drop other roles.
        If not specified,
        <literal>NOCREATEROLE</literal> is the default.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><literal>CREATEUSER</literal></term>
      <term><literal>NOCREATEUSER</literal></term>
      <listitem>
       <para>
        These clauses are an obsolete, but still accepted, spelling of
        <literal>SUPERUSER</literal> and <literal>NOSUPERUSER</literal>.
        Note that they are <emphasis>not</> equivalent to
        <literal>CREATEROLE</literal> as one might naively expect!
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><literal>INHERIT</literal></term>
      <term><literal>NOINHERIT</literal></term>
      <listitem>
       <para>
        These clauses determine whether a role <quote>inherits</> the
        privileges of roles it is a member of.
        A role with the <literal>INHERIT</literal> attribute can automatically
        use whatever database privileges have been granted to all roles
        it is directly or indirectly a member of.
        Without <literal>INHERIT</literal>, membership in another role
        only grants the ability to <command>SET ROLE</> to that other role;
        the privileges of the other role are only available after having
        done so.
        If not specified,
        <literal>INHERIT</literal> is the default.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><literal>LOGIN</literal></term>
      <term><literal>NOLOGIN</literal></term>
      <listitem>
       <para>
        These clauses determine whether a role is allowed to log in;
        that is, whether the role can be given as the initial session
        authorization name during client connection.  A role having
        the <literal>LOGIN</literal> attribute can be thought of as a user.
        Roles without this attribute are useful for managing database
        privileges, but are not users in the usual sense of the word.
        If not specified,
        <literal>NOLOGIN</literal> is the default, except when
        <command>CREATE ROLE</> is invoked through its alternative spelling
        <command>CREATE USER</>.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><literal>CONNECTION LIMIT</literal> <replaceable class="parameter">connlimit</replaceable></term>
      <listitem>
       <para>
        If role can log in, this specifies how many concurrent connections
        the role can make.  -1 (the default) means no limit.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><literal>PASSWORD</> <replaceable class="parameter">password</replaceable></term>
      <listitem>
       <para>
        Sets the role's password.  (A password is only of use for
        roles having the <literal>LOGIN</literal> attribute, but you
        can nonetheless define one for roles without it.)  If you do
        not plan to use password authentication you can omit this
        option.  If no password is specified, the password will be set
        to null and password authentication will always fail for that
        user.  A null password can optionally be written explicitly as
        <literal>PASSWORD NULL</literal>.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><literal>ENCRYPTED</></term>
      <term><literal>UNENCRYPTED</></term>
      <listitem>
       <para>
        These key words control whether the password is stored
        encrypted in the system catalogs.  (If neither is specified,
        the default behavior is determined by the configuration
        parameter <xref linkend="guc-password-encryption">.)  If the
        presented password string is already in MD5-encrypted format,
        then it is stored encrypted as-is, regardless of whether
        <literal>ENCRYPTED</> or <literal>UNENCRYPTED</> is specified
        (since the system cannot decrypt the specified encrypted
        password string).  This allows reloading of encrypted
        passwords during dump/restore.
       </para>

       <para>
        Note that older clients might lack support for the MD5
        authentication mechanism that is needed to work with passwords
        that are stored encrypted.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><literal>VALID UNTIL</literal> '<replaceable class="parameter">timestamp</replaceable>'</term>
      <listitem>
       <para>
        The <literal>VALID UNTIL</literal> clause sets a date and
        time after which the role's password is no longer valid.  If
        this clause is omitted the password will be valid for all time.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><literal>IN ROLE</> <replaceable class="parameter">role_name</replaceable></term>
      <listitem>
       <para>
        The <literal>IN ROLE</literal> clause lists one or more existing
        roles to which the new role will be immediately added as a new
        member.  (Note that there is no option to add the new role as an
        administrator; use a separate <command>GRANT</> command to do that.)
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><literal>IN GROUP</> <replaceable class="parameter">role_name</replaceable></term>
      <listitem>
       <para>
        <literal>IN GROUP</literal> is an obsolete spelling of
        <literal>IN ROLE</>.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><literal>ROLE</> <replaceable class="parameter">role_name</replaceable></term>
      <listitem>
       <para>
        The <literal>ROLE</literal> clause lists one or more existing
        roles which are automatically added as members of the new role.
        (This in effect makes the new role a <quote>group</>.)
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><literal>ADMIN</> <replaceable class="parameter">role_name</replaceable></term>
      <listitem>
       <para>
        The <literal>ADMIN</literal> clause is like <literal>ROLE</literal>,
        but the named roles are added to the new role <literal>WITH ADMIN
        OPTION</>, giving them the right to grant membership in this role
        to others.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><literal>USER</> <replaceable class="parameter">role_name</replaceable></term>
      <listitem>
       <para>
        The <literal>USER</literal> clause is an obsolete spelling of
        the <literal>ROLE</> clause.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><literal>SYSID</> <replaceable class="parameter">uid</replaceable></term>
      <listitem>
       <para>
        The <literal>SYSID</literal> clause is ignored, but is accepted
        for backwards compatibility.
       </para>
      </listitem>
     </varlistentry>
    </variablelist>
 </refsect1> 

 <refsect1>
  <title>Notes</title>

  <para>
   Use <xref linkend="SQL-ALTERROLE"> to
   change the attributes of a role, and <xref linkend="SQL-DROPROLE">
   to remove a role.  All the attributes
   specified by <command>CREATE ROLE</> can be modified by later
   <command>ALTER ROLE</> commands.
  </para>

  <para>
   The preferred way to add and remove members of roles that are being
   used as groups is to use
   <xref linkend="SQL-GRANT"> and
   <xref linkend="SQL-REVOKE">.
  </para>

  <para>
   The <literal>VALID UNTIL</> clause defines an expiration time for a
   password only, not for the role <foreignphrase>per se</>.  In
   particular, the expiration time is not enforced when logging in using
   a non-password-based authentication method.
  </para>

  <para>
   The <literal>INHERIT</> attribute governs inheritance of grantable
   privileges (that is, access privileges for database objects and role
   memberships).  It does not apply to the special role attributes set by
   <command>CREATE ROLE</> and <command>ALTER ROLE</>.  For example, being
   a member of a role with <literal>CREATEDB</> privilege does not immediately
   grant the ability to create databases, even if <literal>INHERIT</> is set;
   it would be necessary to become that role via
   <xref linkend="SQL-SET-ROLE"> before
   creating a database.
  </para>

  <para>
   The <literal>INHERIT</> attribute is the default for reasons of backwards
   compatibility: in prior releases of <productname>PostgreSQL</productname>,
   users always had access to all privileges of groups they were members of.
   However, <literal>NOINHERIT</> provides a closer match to the semantics
   specified in the SQL standard.
  </para>

  <para>
   Be careful with the <literal>CREATEROLE</> privilege. There is no concept of
   inheritance for the privileges of a <literal>CREATEROLE</>-role. That
   means that even if a role does not have a certain privilege but is allowed
   to create other roles, it can easily create another role with different
   privileges than its own (except for creating roles with superuser
   privileges). For example, if the role <quote>user</> has the
   <literal>CREATEROLE</> privilege but not the <literal>CREATEDB</> privilege,
   nonetheless it can create a new role with the <literal>CREATEDB</>
   privilege. Therefore, regard roles that have the <literal>CREATEROLE</>
   privilege as almost-superuser-roles.
  </para>

  <para>
   <productname>PostgreSQL</productname> includes a program <xref
   linkend="APP-CREATEUSER"> that has
   the same functionality as <command>CREATE ROLE</command> (in fact,
   it calls this command) but can be run from the command shell.
  </para>

  <para>
   The <literal>CONNECTION LIMIT</> option is only enforced approximately;
   if two new sessions start at about the same time when just one
   connection <quote>slot</> remains for the role, it is possible that
   both will fail.  Also, the limit is never enforced for superusers.
  </para>

  <para>
   Caution must be exercised when specifying an unencrypted password
   with this command.  The password will be transmitted to the server
   in cleartext, and it might also be logged in the client's command
   history or the server log.  The command <xref
   linkend="APP-CREATEUSER">, however, transmits
   the password encrypted.  Also, <xref linkend="app-psql">
   contains a command
   <command>\password</command> that can be used to safely change the
   password later.
  </para>
 </refsect1>

 <refsect1>
  <title>Examples</title>

  <para>
   Create a role that can log in, but don't give it a password:
<programlisting>
CREATE ROLE jonathan LOGIN;
</programlisting>
  </para>

  <para>
   Create a role with a password:
<programlisting>
CREATE USER davide WITH PASSWORD 'jw8s0F4';
</programlisting>
   (<command>CREATE USER</> is the same as <command>CREATE ROLE</> except
   that it implies <literal>LOGIN</>.)
  </para>

  <para>
   Create a role with a password that is valid until the end of 2004.
   After one second has ticked in 2005, the password is no longer
   valid.

<programlisting>
CREATE ROLE miriam WITH LOGIN PASSWORD 'jw8s0F4' VALID UNTIL '2005-01-01';
</programlisting>
  </para>

  <para> 
   Create a role that can create databases and manage roles:
<programlisting>
CREATE ROLE admin WITH CREATEDB CREATEROLE;
</programlisting>
  </para>
 </refsect1>
 
 <refsect1>
  <title>Compatibility</title>

  <para>
   The <command>CREATE ROLE</command> statement is in the SQL standard,
   but the standard only requires the syntax
<synopsis>
CREATE ROLE <replaceable class="PARAMETER">name</> [ WITH ADMIN <replaceable class="PARAMETER">role_name</> ]
</synopsis>
   Multiple initial administrators, and all the other options of
   <command>CREATE ROLE</command>, are
   <productname>PostgreSQL</productname> extensions.
  </para>
  
  <para>
   The SQL standard defines the concepts of users and roles, but it
   regards them as distinct concepts and leaves all commands defining
   users to be specified by each database implementation.  In
   <productname>PostgreSQL</productname> we have chosen to unify
   users and roles into a single kind of entity.  Roles therefore
   have many more optional attributes than they do in the standard.
  </para>

  <para>
   The behavior specified by the SQL standard is most closely approximated
   by giving users the <literal>NOINHERIT</> attribute, while roles are
   given the <literal>INHERIT</> attribute.
  </para>
 </refsect1>

 <refsect1>
  <title>See Also</title>

  <simplelist type="inline">
   <member><xref linkend="sql-set-role"></member>
   <member><xref linkend="sql-alterrole"></member>
   <member><xref linkend="sql-droprole"></member>
   <member><xref linkend="sql-grant"></member>
   <member><xref linkend="sql-revoke"></member>
   <member><xref linkend="app-createuser"></member>
  </simplelist>
 </refsect1>
</refentry>
