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2d819a08a1
New provider for collations, like "libc" or "icu", but without any external dependency. Initially, the only locale supported by the builtin provider is "C", which is identical to the libc provider's "C" locale. The libc provider's "C" locale has always been treated as a special case that uses an internal implementation, without using libc at all -- so the new builtin provider uses the same implementation. The builtin provider's locale is independent of the server environment variables LC_COLLATE and LC_CTYPE. Using the builtin provider, the database collation locale can be "C" while LC_COLLATE and LC_CTYPE are set to "en_US", which is impossible with the libc provider. By offering a new builtin provider, it clarifies that the semantics of a collation using this provider will never depend on libc, and makes it easier to document the behavior. Discussion: https://postgr.es/m/ab925f69-5f9d-f85e-b87c-bd2a44798659@joeconway.com Discussion: https://postgr.es/m/dd9261f4-7a98-4565-93ec-336c1c110d90@manitou-mail.org Discussion: https://postgr.es/m/ff4c2f2f9c8fc7ca27c1c24ae37ecaeaeaff6b53.camel%40j-davis.com Reviewed-by: Daniel Vérité, Peter Eisentraut, Jeremy Schneider
502 lines
20 KiB
Plaintext
502 lines
20 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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[ ICU_RULES [=] <replaceable class="parameter">icu_rules</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 id="create-database-name">
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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 id="create-database-user-name">
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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 able to <literal>SET ROLE</literal> to that
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role.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry id="create-database-template">
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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 id="create-database-encoding">
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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-ahead
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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 id="create-database-locale">
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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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Sets the default collation order and character classification in the
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new database. Collation affects the sort order applied to strings,
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e.g., in queries with <literal>ORDER BY</literal>, as well as the order used in indexes
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on text columns. Character classification affects the categorization
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of characters, e.g., lower, upper, and digit. Also sets the
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associated aspects of the operating system environment,
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<literal>LC_COLLATE</literal> and <literal>LC_CTYPE</literal>. The
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default is the same setting as the template database. See <xref
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linkend="collation-managing-create-libc"/> and <xref
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linkend="collation-managing-create-icu"/> for details.
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</para>
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<para>
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Can be overridden by setting <xref
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linkend="create-database-lc-collate"/>, <xref
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linkend="create-database-lc-ctype"/>, or <xref
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linkend="create-database-icu-locale"/> individually.
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</para>
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<para>
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If <xref linkend="create-database-locale-provider"/> is
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<literal>builtin</literal>, then <replaceable>locale</replaceable>
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must be specified and set to <literal>C</literal>.
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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 id="create-database-lc-collate">
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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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Sets <literal>LC_COLLATE</literal> in the database server's operating
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system environment. The default is the setting of <xref
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linkend="create-database-locale"/> if specified, otherwise the same
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setting as the template database. See below for additional
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restrictions.
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</para>
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<para>
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If <xref linkend="create-database-locale-provider"/> is
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<literal>libc</literal>, also sets the default collation order to use
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in the new database, overriding the setting <xref
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linkend="create-database-locale"/>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry id="create-database-lc-ctype">
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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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Sets <literal>LC_CTYPE</literal> in the database server's operating
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system environment. The default is the setting of <xref
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linkend="create-database-locale"/> if specified, otherwise the same
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setting as the template database. See below for additional
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restrictions.
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</para>
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<para>
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If <xref linkend="create-database-locale-provider"/> is
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<literal>libc</literal>, also sets the default character
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classification to use in the new database, overriding the setting
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<xref linkend="create-database-locale"/>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry id="create-database-icu-locale">
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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 (see <xref
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linkend="collation-managing-create-icu"/>) for the database default
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collation order and character classification, overriding the setting
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<xref linkend="create-database-locale"/>. The <link
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linkend="create-database-locale-provider">locale provider</link> must be ICU. The default
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is the setting of <xref linkend="create-database-locale"/> if
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specified; otherwise the same setting as the template database.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry id="create-database-icu-rules">
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<term><replaceable class="parameter">icu_rules</replaceable></term>
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<listitem>
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<para>
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Specifies additional collation rules to customize the behavior of the
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default collation of this database. This is supported for ICU only.
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See <xref linkend="icu-tailoring-rules"/> for details.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry id="create-database-locale-provider">
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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 <literal>builtin</literal>,
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<literal>icu</literal><indexterm><primary>ICU</primary></indexterm>
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(if the server was built with ICU support) or <literal>libc</literal>.
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By default, the provider is the same as that of the <xref
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linkend="create-database-template"/>. See <xref
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linkend="locale-providers"/> for details.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry id="create-database-collation-version">
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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 id="create-database-tablespace-name">
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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 id="create-database-allowconn">
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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 id="create-database-connlimit">
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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 id="create-database-istemplate">
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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 id="create-database-oid">
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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, <productname>PostgreSQL</productname>
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will choose a suitable OID automatically. This parameter is primarily
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intended for internal use by <application>pg_upgrade</application>,
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and only <application>pg_upgrade</application> can specify a value
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less 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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|
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<refsect1>
|
|
<title>Examples</title>
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|
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<para>
|
|
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>
|
|
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>
|