451 lines
17 KiB
Plaintext
451 lines
17 KiB
Plaintext
<!--
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doc/src/sgml/ref/create_database.sgml
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PostgreSQL documentation
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-->
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<refentry id="sql-createdatabase">
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<indexterm zone="sql-createdatabase">
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<primary>CREATE DATABASE</primary>
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</indexterm>
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<refmeta>
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<refentrytitle>CREATE DATABASE</refentrytitle>
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<manvolnum>7</manvolnum>
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<refmiscinfo>SQL - Language Statements</refmiscinfo>
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</refmeta>
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<refnamediv>
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<refname>CREATE DATABASE</refname>
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<refpurpose>create a new database</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<synopsis>
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CREATE DATABASE <replaceable class="parameter">name</replaceable>
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[ [ WITH ] [ OWNER [=] <replaceable class="parameter">user_name</replaceable> ]
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[ TEMPLATE [=] <replaceable class="parameter">template</replaceable> ]
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[ ENCODING [=] <replaceable class="parameter">encoding</replaceable> ]
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[ STRATEGY [=] <replaceable class="parameter">strategy</replaceable> ] ]
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[ LOCALE [=] <replaceable class="parameter">locale</replaceable> ]
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[ LC_COLLATE [=] <replaceable class="parameter">lc_collate</replaceable> ]
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[ LC_CTYPE [=] <replaceable class="parameter">lc_ctype</replaceable> ]
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[ ICU_LOCALE [=] <replaceable class="parameter">icu_locale</replaceable> ]
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[ LOCALE_PROVIDER [=] <replaceable class="parameter">locale_provider</replaceable> ]
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[ COLLATION_VERSION = <replaceable>collation_version</replaceable> ]
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[ TABLESPACE [=] <replaceable class="parameter">tablespace_name</replaceable> ]
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[ ALLOW_CONNECTIONS [=] <replaceable class="parameter">allowconn</replaceable> ]
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[ CONNECTION LIMIT [=] <replaceable class="parameter">connlimit</replaceable> ]
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[ IS_TEMPLATE [=] <replaceable class="parameter">istemplate</replaceable> ]
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[ OID [=] <replaceable class="parameter">oid</replaceable> ] ]
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</synopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>
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<command>CREATE DATABASE</command> creates a new
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<productname>PostgreSQL</productname> database.
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</para>
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<para>
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To create a database, you must be a superuser or have the special
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<literal>CREATEDB</literal> privilege.
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See <xref linkend="sql-createrole"/>.
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</para>
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<para>
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By default, the new database will be created by cloning the standard
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system database <literal>template1</literal>. A different template can be
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specified by writing <literal>TEMPLATE
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<replaceable class="parameter">name</replaceable></literal>. In particular,
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by writing <literal>TEMPLATE template0</literal>, you can create a pristine
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database (one where no user-defined objects exist and where the system
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objects have not been altered)
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containing only the standard objects predefined by your
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version of <productname>PostgreSQL</productname>. This is useful
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if you wish to avoid copying
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any installation-local objects that might have been added to
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<literal>template1</literal>.
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</para>
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</refsect1>
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<refsect1>
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<title>Parameters</title>
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<variablelist>
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<varlistentry>
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<term><replaceable class="parameter">name</replaceable></term>
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<listitem>
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<para>
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The name of a database to create.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">user_name</replaceable></term>
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<listitem>
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<para>
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The role name of the user who will own the new database,
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or <literal>DEFAULT</literal> to use the default (namely, the
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user executing the command). To create a database owned by another
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role, you must be a direct or indirect member of that role,
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or be a superuser.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">template</replaceable></term>
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<listitem>
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<para>
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The name of the template from which to create the new database,
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or <literal>DEFAULT</literal> to use the default template
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(<literal>template1</literal>).
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">encoding</replaceable></term>
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<listitem>
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<para>
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Character set encoding to use in the new database. Specify
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a string constant (e.g., <literal>'SQL_ASCII'</literal>),
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or an integer encoding number, or <literal>DEFAULT</literal>
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to use the default encoding (namely, the encoding of the
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template database). The character sets supported by the
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<productname>PostgreSQL</productname> server are described in
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<xref linkend="multibyte-charset-supported"/>. See below for
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additional restrictions.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry id="create-database-strategy" xreflabel="CREATE DATABASE STRATEGY">
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<term><replaceable class="parameter">strategy</replaceable></term>
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<listitem>
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<para>
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Strategy to be used in creating the new database. If
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the <literal>WAL_LOG</literal> strategy is used, the database will be
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copied block by block and each block will be separately written
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to the write-ahead log. This is the most efficient strategy in
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cases where the template database is small, and therefore it is the
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default. The older <literal>FILE_COPY</literal> strategy is also
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available. This strategy writes a small record to the write-ahead log
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for each tablespace used by the target database. Each such record
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represents copying an entire directory to a new location at the
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filesystem level. While this does reduce the write-ahed
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log volume substantially, especially if the template database is large,
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it also forces the system to perform a checkpoint both before and
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after the creation of the new database. In some situations, this may
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have a noticeable negative impact on overall system performance.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">locale</replaceable></term>
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<listitem>
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<para>
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This is a shortcut for setting <symbol>LC_COLLATE</symbol>
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and <symbol>LC_CTYPE</symbol> at once. If you specify this,
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you cannot specify either of those parameters.
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</para>
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<tip>
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<para>
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The other locale settings <xref linkend="guc-lc-messages"/>, <xref
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linkend="guc-lc-monetary"/>, <xref linkend="guc-lc-numeric"/>, and
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<xref linkend="guc-lc-time"/> are not fixed per database and are not
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set by this command. If you want to make them the default for a
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specific database, you can use <literal>ALTER DATABASE
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... SET</literal>.
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</para>
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</tip>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">lc_collate</replaceable></term>
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<listitem>
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<para>
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Collation order (<literal>LC_COLLATE</literal>) to use in the new database.
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This affects the sort order applied to strings, e.g., in queries with
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ORDER BY, as well as the order used in indexes on text columns.
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The default is to use the collation order of the template database.
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See below for additional restrictions.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">lc_ctype</replaceable></term>
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<listitem>
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<para>
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Character classification (<literal>LC_CTYPE</literal>) to use in the new
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database. This affects the categorization of characters, e.g., lower,
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upper and digit. The default is to use the character classification of
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the template database. See below for additional restrictions.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">icu_locale</replaceable></term>
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<listitem>
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<para>
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Specifies the ICU locale ID if the ICU locale provider is used.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable>locale_provider</replaceable></term>
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<listitem>
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<para>
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Specifies the provider to use for the default collation in this
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database. Possible values are:
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<literal>icu</literal>,<indexterm><primary>ICU</primary></indexterm>
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<literal>libc</literal>. <literal>libc</literal> is the default. The
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available choices depend on the operating system and build options.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable>collation_version</replaceable></term>
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<listitem>
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<para>
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Specifies the collation version string to store with the database.
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Normally, this should be omitted, which will cause the version to be
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computed from the actual version of the database collation as provided
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by the operating system. This option is intended to be used by
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<command>pg_upgrade</command> for copying the version from an existing
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installation.
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</para>
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<para>
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See also <xref linkend="sql-alterdatabase"/> for how to handle
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database collation version mismatches.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">tablespace_name</replaceable></term>
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<listitem>
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<para>
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The name of the tablespace that will be associated with the
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new database, or <literal>DEFAULT</literal> to use the
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template database's tablespace. This
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tablespace will be the default tablespace used for objects
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created in this database. See
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<xref linkend="sql-createtablespace"/>
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for more information.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">allowconn</replaceable></term>
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<listitem>
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<para>
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If false then no one can connect to this database. The default is
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true, allowing connections (except as restricted by other mechanisms,
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such as <literal>GRANT</literal>/<literal>REVOKE CONNECT</literal>).
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">connlimit</replaceable></term>
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<listitem>
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<para>
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How many concurrent connections can be made
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to this database. -1 (the default) means no limit.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">istemplate</replaceable></term>
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<listitem>
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<para>
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If true, then this database can be cloned by any user with <literal>CREATEDB</literal>
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privileges; if false (the default), then only superusers or the owner
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of the database can clone it.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">oid</replaceable></term>
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<listitem>
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<para>
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The object identifier to be used for the new database. If this
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parameter is not specified, the database will choose a suitable
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OID automatically. This parameter is primarily intended for internal
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use by <application>pg_upgrade</application>, and only
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<application>pg_upgrade</application> can specify a value less
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than 16384.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>
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Optional parameters can be written in any order, not only the order
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illustrated above.
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</para>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para>
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<command>CREATE DATABASE</command> cannot be executed inside a transaction
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block.
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</para>
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<para>
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Errors along the line of <quote>could not initialize database directory</quote>
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are most likely related to insufficient permissions on the data
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directory, a full disk, or other file system problems.
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</para>
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<para>
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Use <link linkend="sql-dropdatabase"><command>DROP DATABASE</command></link> to remove a database.
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</para>
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<para>
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The program <xref linkend="app-createdb"/> is a
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wrapper program around this command, provided for convenience.
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</para>
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<para>
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Database-level configuration parameters (set via <link
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linkend="sql-alterdatabase"><command>ALTER DATABASE</command></link>) and database-level permissions (set via
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<link linkend="sql-grant"><command>GRANT</command></link>) are not copied from the template database.
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</para>
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<para>
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Although it is possible to copy a database other than <literal>template1</literal>
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by specifying its name as the template, this is not (yet) intended as
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a general-purpose <quote><command>COPY DATABASE</command></quote> facility.
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The principal limitation is that no other sessions can be connected to
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the template database while it is being copied. <command>CREATE
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DATABASE</command> will fail if any other connection exists when it starts;
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otherwise, new connections to the template database are locked out
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until <command>CREATE DATABASE</command> completes.
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See <xref linkend="manage-ag-templatedbs"/> for more information.
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</para>
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<para>
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The character set encoding specified for the new database must be
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compatible with the chosen locale settings (<literal>LC_COLLATE</literal> and
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<literal>LC_CTYPE</literal>). If the locale is <literal>C</literal> (or equivalently
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<literal>POSIX</literal>), then all encodings are allowed, but for other
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locale settings there is only one encoding that will work properly.
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(On Windows, however, UTF-8 encoding can be used with any locale.)
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<command>CREATE DATABASE</command> will allow superusers to specify
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<literal>SQL_ASCII</literal> encoding regardless of the locale settings,
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but this choice is deprecated and may result in misbehavior of
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character-string functions if data that is not encoding-compatible
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with the locale is stored in the database.
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</para>
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<para>
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The encoding and locale settings must match those of the template database,
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except when <literal>template0</literal> is used as template. This is because
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other databases might contain data that does not match the specified
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encoding, or might contain indexes whose sort ordering is affected by
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<literal>LC_COLLATE</literal> and <literal>LC_CTYPE</literal>. Copying such data would
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result in a database that is corrupt according to the new settings.
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<literal>template0</literal>, however, is known to not contain any data or
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indexes that would be affected.
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</para>
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<para>
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There is currently no option to use a database locale with nondeterministic
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comparisons (see <link linkend="sql-createcollation"><command>CREATE
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COLLATION</command></link> for an explanation). If this is needed, then
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per-column collations would need to be used.
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</para>
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<para>
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The <literal>CONNECTION LIMIT</literal> option is only enforced approximately;
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if two new sessions start at about the same time when just one
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connection <quote>slot</quote> remains for the database, it is possible that
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both will fail. Also, the limit is not enforced against superusers or
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background worker processes.
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</para>
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</refsect1>
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<refsect1>
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<title>Examples</title>
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<para>
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To create a new database:
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<programlisting>
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CREATE DATABASE lusiadas;
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</programlisting>
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</para>
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<para>
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To create a database <literal>sales</literal> owned by user <literal>salesapp</literal>
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with a default tablespace of <literal>salesspace</literal>:
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<programlisting>
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CREATE DATABASE sales OWNER salesapp TABLESPACE salesspace;
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</programlisting>
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</para>
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<para>
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To create a database <literal>music</literal> with a different locale:
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<programlisting>
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CREATE DATABASE music
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LOCALE 'sv_SE.utf8'
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TEMPLATE template0;
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</programlisting>
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In this example, the <literal>TEMPLATE template0</literal> clause is required if
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the specified locale is different from the one in <literal>template1</literal>.
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(If it is not, then specifying the locale explicitly is redundant.)
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</para>
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<para>
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To create a database <literal>music2</literal> with a different locale and a
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different character set encoding:
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<programlisting>
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CREATE DATABASE music2
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LOCALE 'sv_SE.iso885915'
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ENCODING LATIN9
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TEMPLATE template0;
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</programlisting>
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The specified locale and encoding settings must match, or an error will be
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reported.
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</para>
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<para>
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Note that locale names are specific to the operating system, so that the
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above commands might not work in the same way everywhere.
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</para>
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</refsect1>
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<refsect1>
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<title>Compatibility</title>
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|
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<para>
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There is no <command>CREATE DATABASE</command> statement in the SQL
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standard. Databases are equivalent to catalogs, whose creation is
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implementation-defined.
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</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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|
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<simplelist type="inline">
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<member><xref linkend="sql-alterdatabase"/></member>
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<member><xref linkend="sql-dropdatabase"/></member>
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</simplelist>
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</refsect1>
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</refentry>
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