doc/src/sgml/ref/create_schema.sgml

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doc/src/sgml/ref/create_schema.sgml
PostgreSQL documentation
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<refentry id="sql-createschema">
 <indexterm zone="sql-createschema">
  <primary>CREATE SCHEMA</primary>
 </indexterm>

 <refmeta>
  <refentrytitle>CREATE SCHEMA</refentrytitle>
  <manvolnum>7</manvolnum>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>CREATE SCHEMA</refname>
  <refpurpose>define a new schema</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
<synopsis>
CREATE SCHEMA <replaceable class="parameter">schema_name</replaceable> [ AUTHORIZATION <replaceable class="parameter">role_specification</replaceable> ] [ <replaceable class="parameter">schema_element</replaceable> [ ... ] ]
CREATE SCHEMA AUTHORIZATION <replaceable class="parameter">role_specification</replaceable> [ <replaceable class="parameter">schema_element</replaceable> [ ... ] ]
CREATE SCHEMA IF NOT EXISTS <replaceable class="parameter">schema_name</replaceable> [ AUTHORIZATION <replaceable class="parameter">role_specification</replaceable> ]
CREATE SCHEMA IF NOT EXISTS AUTHORIZATION <replaceable class="parameter">role_specification</replaceable>

<phrase>where <replaceable class="parameter">role_specification</replaceable> can be:</phrase>

    <replaceable class="parameter">user_name</replaceable>
  | CURRENT_ROLE
  | CURRENT_USER
  | SESSION_USER
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <command>CREATE SCHEMA</command> enters a new schema
   into the current database.
   The schema name must be distinct from the name of any existing schema
   in the current database.
  </para>

  <para>
   A schema is essentially a namespace:
   it contains named objects (tables, data types, functions, and operators)
   whose names can duplicate those of other objects existing in other
   schemas.  Named objects are accessed either by <quote>qualifying</quote>
   their names with the schema name as a prefix, or by setting a search
   path that includes the desired schema(s).  A <literal>CREATE</literal> command
   specifying an unqualified object name creates the object
   in the current schema (the one at the front of the search path,
   which can be determined with the function <function>current_schema</function>).
  </para>

  <para>
   Optionally, <command>CREATE SCHEMA</command> can include subcommands
   to create objects within the new schema.  The subcommands are treated
   essentially the same as separate commands issued after creating the
   schema, except that if the <literal>AUTHORIZATION</literal> clause is used,
   all the created objects will be owned by that user.
  </para>
 </refsect1>

 <refsect1>
  <title>Parameters</title>

    <variablelist>
     <varlistentry>
      <term><replaceable class="parameter">schema_name</replaceable></term>
      <listitem>
       <para>
        The name of a schema to be created.  If this is omitted, the
        <replaceable class="parameter">user_name</replaceable>
        is used as the schema name.  The name cannot
        begin with <literal>pg_</literal>, as such names
        are reserved for system schemas.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><replaceable class="parameter">user_name</replaceable></term>
      <listitem>
       <para>
        The role name of the user who will own the new schema.  If omitted,
        defaults to the user executing the command.  To create a schema
        owned by another role, you must be a direct or indirect member of
        that role, or be a superuser.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><replaceable class="parameter">schema_element</replaceable></term>
      <listitem>
       <para>
        An SQL statement defining an object to be created within the
        schema. Currently, only <command>CREATE
        TABLE</command>, <command>CREATE VIEW</command>, <command>CREATE
        INDEX</command>, <command>CREATE SEQUENCE</command>, <command>CREATE
        TRIGGER</command> and <command>GRANT</command> are accepted as clauses
        within <command>CREATE SCHEMA</command>. Other kinds of objects may
        be created in separate commands after the schema is created.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><literal>IF NOT EXISTS</literal></term>
      <listitem>
       <para>
        Do nothing (except issuing a notice) if a schema with the same name
        already exists.  <replaceable class="parameter">schema_element</replaceable>
        subcommands cannot be included when this option is used.
       </para>
      </listitem>
     </varlistentry>
    </variablelist>
 </refsect1>

 <refsect1>
  <title>Notes</title>

  <para>
   To create a schema, the invoking user must have the
   <literal>CREATE</literal> privilege for the current database.
   (Of course, superusers bypass this check.)
  </para>
 </refsect1>

 <refsect1>
  <title>Examples</title>

  <para>
   Create a schema:
<programlisting>
CREATE SCHEMA myschema;
</programlisting>
  </para>

  <para>
   Create a schema for user <literal>joe</literal>; the schema will also be
   named <literal>joe</literal>:
<programlisting>
CREATE SCHEMA AUTHORIZATION joe;
</programlisting>
  </para>

  <para>
   Create a schema named <literal>test</literal> that will be owned by user
   <literal>joe</literal>, unless there already is a schema named <literal>test</literal>.
   (It does not matter whether <literal>joe</literal> owns the pre-existing schema.)
<programlisting>
CREATE SCHEMA IF NOT EXISTS test AUTHORIZATION joe;
</programlisting>
  </para>

  <para>
   Create a schema and create a table and view within it:
<programlisting>
CREATE SCHEMA hollywood
    CREATE TABLE films (title text, release date, awards text[])
    CREATE VIEW winners AS
        SELECT title, release FROM films WHERE awards IS NOT NULL;
</programlisting>
   Notice that the individual subcommands do not end with semicolons.
  </para>

  <para>
   The following is an equivalent way of accomplishing the same result:
<programlisting>
CREATE SCHEMA hollywood;
CREATE TABLE hollywood.films (title text, release date, awards text[]);
CREATE VIEW hollywood.winners AS
    SELECT title, release FROM hollywood.films WHERE awards IS NOT NULL;
</programlisting></para>

 </refsect1>

 <refsect1>
  <title>Compatibility</title>

  <para>
   The SQL standard allows a <literal>DEFAULT CHARACTER SET</literal> clause
   in <command>CREATE SCHEMA</command>, as well as more subcommand
   types than are presently accepted by
   <productname>PostgreSQL</productname>.
  </para>

  <para>
   The SQL standard specifies that the subcommands in <command>CREATE
   SCHEMA</command> can appear in any order.  The present
   <productname>PostgreSQL</productname> implementation does not
   handle all cases of forward references in subcommands; it might
   sometimes be necessary to reorder the subcommands in order to avoid
   forward references.
  </para>

  <para>
   According to the SQL standard, the owner of a schema always owns
   all objects within it.  <productname>PostgreSQL</productname>
   allows schemas to contain objects owned by users other than the
   schema owner.  This can happen only if the schema owner grants the
   <literal>CREATE</literal> privilege on their schema to someone else, or a
   superuser chooses to create objects in it.
  </para>

  <para>
   The <literal>IF NOT EXISTS</literal> option is a
   <productname>PostgreSQL</productname> extension.
  </para>
 </refsect1>

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

  <simplelist type="inline">
   <member><xref linkend="sql-alterschema"/></member>
   <member><xref linkend="sql-dropschema"/></member>
 </simplelist>
 </refsect1>

</refentry>