<!--
doc/src/sgml/ref/create_database.sgml
PostgreSQL documentation
-->

<refentry id="sql-createdatabase">
 <indexterm zone="sql-createdatabase">
  <primary>CREATE DATABASE</primary>
 </indexterm>

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

 <refnamediv>
  <refname>CREATE DATABASE</refname>
  <refpurpose>create a new database</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
<synopsis>
CREATE DATABASE <replaceable class="parameter">name</replaceable>
    [ WITH ] [ OWNER [=] <replaceable class="parameter">user_name</replaceable> ]
           [ TEMPLATE [=] <replaceable class="parameter">template</replaceable> ]
           [ ENCODING [=] <replaceable class="parameter">encoding</replaceable> ]
           [ STRATEGY [=] <replaceable class="parameter">strategy</replaceable> ]
           [ LOCALE [=] <replaceable class="parameter">locale</replaceable> ]
           [ LC_COLLATE [=] <replaceable class="parameter">lc_collate</replaceable> ]
           [ LC_CTYPE [=] <replaceable class="parameter">lc_ctype</replaceable> ]
           [ ICU_LOCALE [=] <replaceable class="parameter">icu_locale</replaceable> ]
           [ ICU_RULES [=] <replaceable class="parameter">icu_rules</replaceable> ]
           [ LOCALE_PROVIDER [=] <replaceable class="parameter">locale_provider</replaceable> ]
           [ COLLATION_VERSION = <replaceable>collation_version</replaceable> ]
           [ TABLESPACE [=] <replaceable class="parameter">tablespace_name</replaceable> ]
           [ ALLOW_CONNECTIONS [=] <replaceable class="parameter">allowconn</replaceable> ]
           [ CONNECTION LIMIT [=] <replaceable class="parameter">connlimit</replaceable> ]
           [ IS_TEMPLATE [=] <replaceable class="parameter">istemplate</replaceable> ]
           [ OID [=] <replaceable class="parameter">oid</replaceable> ]
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <command>CREATE DATABASE</command> creates a new
   <productname>PostgreSQL</productname> database.
  </para>

  <para>
   To create a database, you must be a superuser or have the special
   <literal>CREATEDB</literal> privilege.
   See <xref linkend="sql-createrole"/>.
  </para>

  <para>
   By default, the new database will be created by cloning the standard
   system database <literal>template1</literal>.  A different template can be
   specified by writing <literal>TEMPLATE
   <replaceable class="parameter">name</replaceable></literal>.  In particular,
   by writing <literal>TEMPLATE template0</literal>, you can create a pristine
   database (one where no user-defined objects exist and where the system
   objects have not been altered)
   containing only the standard objects predefined by your
   version of <productname>PostgreSQL</productname>.  This is useful
   if you wish to avoid copying
   any installation-local objects that might have been added to
   <literal>template1</literal>.
  </para>
 </refsect1>

 <refsect1>
  <title>Parameters</title>

    <variablelist>
     <varlistentry id="create-database-name">
      <term><replaceable class="parameter">name</replaceable></term>
      <listitem>
       <para>
        The name of a database to create.
       </para>
      </listitem>
     </varlistentry>
     <varlistentry id="create-database-user-name">
      <term><replaceable class="parameter">user_name</replaceable></term>
      <listitem>
       <para>
        The role name of the user who will own the new database,
        or <literal>DEFAULT</literal> to use the default (namely, the
        user executing the command).  To create a database owned by another
        role, you must be able to <literal>SET ROLE</literal> to that
        role.
       </para>
      </listitem>
     </varlistentry>
     <varlistentry id="create-database-template">
      <term><replaceable class="parameter">template</replaceable></term>
      <listitem>
       <para>
        The name of the template from which to create the new database,
        or <literal>DEFAULT</literal> to use the default template
        (<literal>template1</literal>).
       </para>
      </listitem>
     </varlistentry>
     <varlistentry id="create-database-encoding">
      <term><replaceable class="parameter">encoding</replaceable></term>
      <listitem>
       <para>
        Character set encoding to use in the new database.  Specify
        a string constant (e.g., <literal>'SQL_ASCII'</literal>),
        or an integer encoding number, or <literal>DEFAULT</literal>
        to use the default encoding (namely, the encoding of the
        template database). The character sets supported by the
        <productname>PostgreSQL</productname> server are described in
        <xref linkend="multibyte-charset-supported"/>. See below for
        additional restrictions.
       </para>
      </listitem>
     </varlistentry>
     <varlistentry id="create-database-strategy" xreflabel="CREATE DATABASE STRATEGY">
      <term><replaceable class="parameter">strategy</replaceable></term>
      <listitem>
       <para>
        Strategy to be used in creating the new database.  If
        the <literal>WAL_LOG</literal> strategy is used, the database will be
        copied block by block and each block will be separately written
        to the write-ahead log. This is the most efficient strategy in
        cases where the template database is small, and therefore it is the
        default. The older <literal>FILE_COPY</literal> strategy is also
        available. This strategy writes a small record to the write-ahead log
        for each tablespace used by the target database. Each such record
        represents copying an entire directory to a new location at the
        filesystem level. While this does reduce the write-ahead
        log volume substantially, especially if the template database is large,
        it also forces the system to perform a checkpoint both before and
        after the creation of the new database. In some situations, this may
        have a noticeable negative impact on overall system performance.
       </para>
      </listitem>
     </varlistentry>
     <varlistentry id="create-database-locale">
      <term><replaceable class="parameter">locale</replaceable></term>
      <listitem>
       <para>
        Sets the default collation order and character classification in the
        new database.  Collation affects the sort order applied to strings,
        e.g., in queries with <literal>ORDER BY</literal>, as well as the order used in indexes
        on text columns.  Character classification affects the categorization
        of characters, e.g., lower, upper, and digit.  Also sets the
        associated aspects of the operating system environment,
        <literal>LC_COLLATE</literal> and <literal>LC_CTYPE</literal>.  The
        default is the same setting as the template database.  See <xref
        linkend="collation-managing-create-libc"/> and <xref
        linkend="collation-managing-create-icu"/> for details.
       </para>
       <para>
        Can be overridden by setting <xref
        linkend="create-database-lc-collate"/>, <xref
        linkend="create-database-lc-ctype"/>, or <xref
        linkend="create-database-icu-locale"/> individually.
       </para>
       <tip>
        <para>
         The other locale settings <xref linkend="guc-lc-messages"/>, <xref
         linkend="guc-lc-monetary"/>, <xref linkend="guc-lc-numeric"/>, and
         <xref linkend="guc-lc-time"/> are not fixed per database and are not
         set by this command.  If you want to make them the default for a
         specific database, you can use <literal>ALTER DATABASE
         ... SET</literal>.
        </para>
       </tip>
      </listitem>
     </varlistentry>
     <varlistentry id="create-database-lc-collate">
      <term><replaceable class="parameter">lc_collate</replaceable></term>
      <listitem>
       <para>
        Sets <literal>LC_COLLATE</literal> in the database server's operating
        system environment.  The default is the setting of <xref
        linkend="create-database-locale"/> if specified, otherwise the same
        setting as the template database.  See below for additional
        restrictions.
       </para>
       <para>
        If <xref linkend="create-database-locale-provider"/> is
        <literal>libc</literal>, also sets the default collation order to use
        in the new database, overriding the setting <xref
        linkend="create-database-locale"/>.
       </para>
      </listitem>
     </varlistentry>
     <varlistentry id="create-database-lc-ctype">
      <term><replaceable class="parameter">lc_ctype</replaceable></term>
      <listitem>
       <para>
        Sets <literal>LC_CTYPE</literal> in the database server's operating
        system environment.  The default is the setting of <xref
        linkend="create-database-locale"/> if specified, otherwise the same
        setting as the template database.  See below for additional
        restrictions.
       </para>
       <para>
        If <xref linkend="create-database-locale-provider"/> is
        <literal>libc</literal>, also sets the default character
        classification to use in the new database, overriding the setting
        <xref linkend="create-database-locale"/>.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry id="create-database-icu-locale">
      <term><replaceable class="parameter">icu_locale</replaceable></term>
      <listitem>
       <para>
        Specifies the ICU locale (see <xref
        linkend="collation-managing-create-icu"/>) for the database default
        collation order and character classification, overriding the setting
        <xref linkend="create-database-locale"/>.  The <link
        linkend="create-database-locale-provider">locale provider</link> must be ICU.  The default
        is the setting of <xref linkend="create-database-locale"/> if
        specified; otherwise the same setting as the template database.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry id="create-database-icu-rules">
      <term><replaceable class="parameter">icu_rules</replaceable></term>
      <listitem>
       <para>
        Specifies additional collation rules to customize the behavior of the
        default collation of this database.  This is supported for ICU only.
        See <xref linkend="icu-tailoring-rules"/> for details.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry id="create-database-locale-provider">
      <term><replaceable>locale_provider</replaceable></term>

      <listitem>
       <para>
        Specifies the provider to use for the default collation in this
        database.  Possible values are
        <literal>icu</literal><indexterm><primary>ICU</primary></indexterm>
        (if the server was built with ICU support) or <literal>libc</literal>.
        By default, the provider is the same as that of the <xref
        linkend="create-database-template"/>. See <xref
        linkend="locale-providers"/> for details.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry id="create-database-collation-version">
      <term><replaceable>collation_version</replaceable></term>

      <listitem>
       <para>
        Specifies the collation version string to store with the database.
        Normally, this should be omitted, which will cause the version to be
        computed from the actual version of the database collation as provided
        by the operating system.  This option is intended to be used by
        <command>pg_upgrade</command> for copying the version from an existing
        installation.
       </para>

       <para>
        See also <xref linkend="sql-alterdatabase"/> for how to handle
        database collation version mismatches.
       </para>
     </listitem>
    </varlistentry>
     <varlistentry id="create-database-tablespace-name">
      <term><replaceable class="parameter">tablespace_name</replaceable></term>
      <listitem>
       <para>
        The name of the tablespace that will be associated with the
        new database, or <literal>DEFAULT</literal> to use the
        template database's tablespace. This
        tablespace will be the default tablespace used for objects
        created in this database. See
        <xref linkend="sql-createtablespace"/>
        for more information.
       </para>
      </listitem>
     </varlistentry>

      <varlistentry id="create-database-allowconn">
       <term><replaceable class="parameter">allowconn</replaceable></term>
       <listitem>
        <para>
         If false then no one can connect to this database.  The default is
         true, allowing connections (except as restricted by other mechanisms,
         such as <literal>GRANT</literal>/<literal>REVOKE CONNECT</literal>).
        </para>
       </listitem>
      </varlistentry>

      <varlistentry id="create-database-connlimit">
      <term><replaceable class="parameter">connlimit</replaceable></term>
      <listitem>
       <para>
        How many concurrent connections can be made
        to this database.  -1 (the default) means no limit.
       </para>
      </listitem>
     </varlistentry>

      <varlistentry id="create-database-istemplate">
       <term><replaceable class="parameter">istemplate</replaceable></term>
       <listitem>
        <para>
         If true, then this database can be cloned by any user with <literal>CREATEDB</literal>
         privileges; if false (the default), then only superusers or the owner
         of the database can clone it.
        </para>
       </listitem>
      </varlistentry>

      <varlistentry id="create-database-oid">
       <term><replaceable class="parameter">oid</replaceable></term>
       <listitem>
        <para>
         The object identifier to be used for the new database. If this
         parameter is not specified, <productname>PostgreSQL</productname>
         will choose a suitable OID automatically. This parameter is primarily
         intended for internal use by <application>pg_upgrade</application>,
         and only <application>pg_upgrade</application> can specify a value
         less than 16384.
        </para>
       </listitem>
      </varlistentry>

    </variablelist>

  <para>
   Optional parameters can be written in any order, not only the order
   illustrated above.
  </para>
 </refsect1>

 <refsect1>
  <title>Notes</title>

   <para>
    <command>CREATE DATABASE</command> cannot be executed inside a transaction
    block.
   </para>

   <para>
    Errors along the line of <quote>could not initialize database directory</quote>
    are most likely related to insufficient permissions on the data
    directory, a full disk, or other file system problems.
   </para>

   <para>
    Use <link linkend="sql-dropdatabase"><command>DROP DATABASE</command></link> to remove a database.
   </para>

   <para>
    The program <xref linkend="app-createdb"/> is a
    wrapper program around this command, provided for convenience.
   </para>

   <para>
    Database-level configuration parameters (set via <link
    linkend="sql-alterdatabase"><command>ALTER DATABASE</command></link>) and database-level permissions (set via
    <link linkend="sql-grant"><command>GRANT</command></link>) are not copied from the template database.
   </para>

  <para>
   Although it is possible to copy a database other than <literal>template1</literal>
   by specifying its name as the template, this is not (yet) intended as
   a general-purpose <quote><command>COPY DATABASE</command></quote> facility.
   The principal limitation is that no other sessions can be connected to
   the template database while it is being copied.  <command>CREATE
   DATABASE</command> will fail if any other connection exists when it starts;
   otherwise, new connections to the template database are locked out
   until <command>CREATE DATABASE</command> completes.
   See <xref linkend="manage-ag-templatedbs"/> for more information.
  </para>

  <para>
   The character set encoding specified for the new database must be
   compatible with the chosen locale settings (<literal>LC_COLLATE</literal> and
   <literal>LC_CTYPE</literal>).  If the locale is <literal>C</literal> (or equivalently
   <literal>POSIX</literal>), then all encodings are allowed, but for other
   locale settings there is only one encoding that will work properly.
   (On Windows, however, UTF-8 encoding can be used with any locale.)
   <command>CREATE DATABASE</command> will allow superusers to specify
   <literal>SQL_ASCII</literal> encoding regardless of the locale settings,
   but this choice is deprecated and may result in misbehavior of
   character-string functions if data that is not encoding-compatible
   with the locale is stored in the database.
  </para>

  <para>
   The encoding and locale settings must match those of the template database,
   except when <literal>template0</literal> is used as template.  This is because
   other databases might contain data that does not match the specified
   encoding, or might contain indexes whose sort ordering is affected by
   <literal>LC_COLLATE</literal> and <literal>LC_CTYPE</literal>.  Copying such data would
   result in a database that is corrupt according to the new settings.
   <literal>template0</literal>, however, is known to not contain any data or
   indexes that would be affected.
  </para>

  <para>
   There is currently no option to use a database locale with nondeterministic
   comparisons (see <link linkend="sql-createcollation"><command>CREATE
   COLLATION</command></link> for an explanation).  If this is needed, then
   per-column collations would need to be used.
  </para>

  <para>
   The <literal>CONNECTION LIMIT</literal> option is only enforced approximately;
   if two new sessions start at about the same time when just one
   connection <quote>slot</quote> remains for the database, it is possible that
   both will fail.  Also, the limit is not enforced against superusers or
   background worker processes.
  </para>
 </refsect1>

 <refsect1>
  <title>Examples</title>

  <para>
   To create a new database:

<programlisting>
CREATE DATABASE lusiadas;
</programlisting>
  </para>

  <para>
   To create a database <literal>sales</literal> owned by user <literal>salesapp</literal>
   with a default tablespace of <literal>salesspace</literal>:

<programlisting>
CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;
</programlisting>
  </para>

  <para>
   To create a database <literal>music</literal> with a different locale:
<programlisting>
CREATE DATABASE music
    LOCALE 'sv_SE.utf8'
    TEMPLATE template0;
</programlisting>
    In this example, the <literal>TEMPLATE template0</literal> clause is required if
    the specified locale is different from the one in <literal>template1</literal>.
    (If it is not, then specifying the locale explicitly is redundant.)
  </para>

  <para>
   To create a database <literal>music2</literal> with a different locale and a
   different character set encoding:
<programlisting>
CREATE DATABASE music2
    LOCALE 'sv_SE.iso885915'
    ENCODING LATIN9
    TEMPLATE template0;
</programlisting>
   The specified locale and encoding settings must match, or an error will be
   reported.
  </para>

  <para>
   Note that locale names are specific to the operating system, so that the
   above commands might not work in the same way everywhere.
  </para>
 </refsect1>

 <refsect1>
  <title>Compatibility</title>

  <para>
   There is no <command>CREATE DATABASE</command> statement in the SQL
   standard.  Databases are equivalent to catalogs, whose creation is
   implementation-defined.
  </para>
 </refsect1>

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

  <simplelist type="inline">
   <member><xref linkend="sql-alterdatabase"/></member>
   <member><xref linkend="sql-dropdatabase"/></member>
  </simplelist>
 </refsect1>

</refentry>
