create_database.sgml

postgresql8.3.4源码,开源数据库

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$PostgreSQL: pgsql/doc/src/sgml/ref/create_database.sgml,v 1.48 2007/09/28 22:25:49 tgl Exp $
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<refentry id="SQL-CREATEDATABASE">
 <refmeta>
  <refentrytitle id="sql-createdatabase-title">CREATE DATABASE</refentrytitle>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

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

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

 <refsynopsisdiv>
<synopsis>
CREATE DATABASE <replaceable class="PARAMETER">name</replaceable>
    [ [ WITH ] [ OWNER [=] <replaceable class="parameter">dbowner</replaceable> ]
           [ TEMPLATE [=] <replaceable class="parameter">template</replaceable> ]
           [ ENCODING [=] <replaceable class="parameter">encoding</replaceable> ]
           [ TABLESPACE [=] <replaceable class="parameter">tablespace</replaceable> ]
           [ CONNECTION LIMIT [=] <replaceable class="parameter">connlimit</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</> privilege.
   See <xref linkend="SQL-CREATEUSER" endterm="SQL-CREATEUSER-title">.
  </para>

  <para>
   Normally, the creator becomes the owner of the new database.
   Superusers can create databases owned by other users, by using the
   <literal>OWNER</> clause. They can even create databases owned by
   users with no special privileges. Non-superusers with <literal>CREATEDB</>
   privilege can only create databases owned by themselves.
  </para>

  <para>
   By default, the new database will be created by cloning the standard
   system database <literal>template1</>.  A different template can be
   specified by writing <literal>TEMPLATE
   <replaceable class="parameter">name</replaceable></literal>.  In particular,
   by writing <literal>TEMPLATE template0</>, you can create a virgin
   database 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</>.
  </para>
 </refsect1>

 <refsect1>
  <title>Parameters</title>

    <variablelist>
     <varlistentry>
      <term><replaceable class="parameter">name</replaceable></term>
      <listitem>
       <para>
        The name of a database to create.
       </para>
      </listitem>
     </varlistentry>
     <varlistentry>
      <term><replaceable class="parameter">dbowner</replaceable></term>
      <listitem>
       <para>
        The name of the database user who will own the new database,
        or <literal>DEFAULT</literal> to use the default (namely, the
        user executing the command).
       </para>
      </listitem>
     </varlistentry>
     <varlistentry>
      <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>
      <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>
      <term><replaceable class="parameter">tablespace</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" endterm="sql-createtablespace-title">
        for more information.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <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>
    </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</> cannot be executed inside a transaction
    block.
   </para>

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

   <para>
    Use <xref linkend="SQL-DROPDATABASE" endterm="SQL-DROPDATABASE-title"> to remove a database.
   </para>

   <para>
    The program <xref linkend="APP-CREATEDB" endterm="APP-CREATEDB-title"> is a
    wrapper program around this command, provided for convenience.
   </para>

  <para>
   Although it is possible to copy a database other than <literal>template1</>
   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</> will fail if any other connection exists when it starts;
   otherwise, new connections to the template database are locked out
   until <command>CREATE DATABASE</> completes.
   See <xref linkend="manage-ag-templatedbs"> for more information.
  </para>

  <para>
   Any character set encoding specified for the new database must be
   compatible with the server's <envar>LC_CTYPE</> locale setting.
   If <envar>LC_CTYPE</> is <literal>C</> (or equivalently
   <literal>POSIX</>), then all encodings are allowed, but for other
   locale settings there is only one encoding that will work properly,
   and so the apparent freedom to specify an encoding is illusory if
   you didn't initialize the database cluster in <literal>C</> locale.
   <command>CREATE DATABASE</> will allow superusers to specify
   <literal>SQL_ASCII</> encoding regardless of the locale setting,
   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 <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 database, it is possible that
   both will fail.  Also, the limit is not enforced against superusers.
  </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</> owned by user <literal>salesapp</>
   with a default tablespace of <literal>salesspace</>:

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

  <para>
   To create a database <literal>music</> which supports the ISO-8859-1 
   character set:

<programlisting>
CREATE DATABASE music ENCODING 'LATIN1';
</programlisting>
  </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" endterm="sql-alterdatabase-title"></member>
   <member><xref linkend="sql-dropdatabase" endterm="sql-dropdatabase-title"></member>
  </simplelist>
 </refsect1>

</refentry>