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bb4eefe7bf
DocBook XML is superficially compatible with DocBook SGML but has a slightly stricter DTD that we have been violating in a few cases. Although XSLT doesn't care whether the document is valid, the style sheets don't necessarily process invalid documents correctly, so we need to work toward fixing this. This first commit moves the indexterms in refentry elements to an allowed position. It has no impact on the output.
236 lines
7.4 KiB
Text
236 lines
7.4 KiB
Text
<!-- doc/src/sgml/ref/create_foreign_table.sgml -->
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<refentry id="SQL-CREATEFOREIGNTABLE">
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<indexterm zone="sql-createforeigntable">
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<primary>CREATE FOREIGN TABLE</primary>
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</indexterm>
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<refmeta>
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<refentrytitle>CREATE FOREIGN TABLE</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 FOREIGN TABLE</refname>
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<refpurpose>define a new foreign table</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<synopsis>
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CREATE FOREIGN TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name</replaceable> ( [
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<replaceable class="PARAMETER">column_name</replaceable> <replaceable class="PARAMETER">data_type</replaceable> [ OPTIONS ( <replaceable class="PARAMETER">option</replaceable> '<replaceable class="PARAMETER">value</replaceable>' [, ... ] ) ] [ COLLATE <replaceable>collation</replaceable> ] [ <replaceable class="PARAMETER">column_constraint</replaceable> [ ... ] ]
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[, ... ]
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] )
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SERVER <replaceable class="parameter">server_name</replaceable>
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[ OPTIONS ( <replaceable class="PARAMETER">option</replaceable> '<replaceable class="PARAMETER">value</replaceable>' [, ... ] ) ]
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<phrase>where <replaceable class="PARAMETER">column_constraint</replaceable> is:</phrase>
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[ CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> ]
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{ NOT NULL |
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NULL |
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DEFAULT <replaceable>default_expr</replaceable> }
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</synopsis>
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</refsynopsisdiv>
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<refsect1 id="SQL-CREATEFOREIGNTABLE-description">
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<title>Description</title>
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<para>
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<command>CREATE FOREIGN TABLE</command> creates a new foreign table
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in the current database. The table will be owned by the user issuing the
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command.
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</para>
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<para>
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If a schema name is given (for example, <literal>CREATE FOREIGN TABLE
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myschema.mytable ...</>) then the table is created in the specified
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schema. Otherwise it is created in the current schema.
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The name of the foreign table must be
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distinct from the name of any other foreign table, table, sequence, index,
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or view in the same schema.
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</para>
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<para>
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<command>CREATE FOREIGN TABLE</command> also automatically creates a data
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type that represents the composite type corresponding to one row of
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the foreign table. Therefore, foreign tables cannot have the same
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name as any existing data type in the same schema.
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</para>
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<para>
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To be able to create a foreign table, you must have <literal>USAGE</literal>
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privilege on the foreign server, as well as <literal>USAGE</literal>
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privilege on all column types used in the table.
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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><literal>IF NOT EXISTS</></term>
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<listitem>
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<para>
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Do not throw an error if a relation with the same name already exists.
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A notice is issued in this case. Note that there is no guarantee that
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the existing relation is anything like the one that would have been
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created.
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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">table_name</replaceable></term>
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<listitem>
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<para>
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The name (optionally schema-qualified) of the table to be created.
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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">column_name</replaceable></term>
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<listitem>
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<para>
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The name of a column to be created in the new table.
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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">data_type</replaceable></term>
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<listitem>
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<para>
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The data type of the column. This can include array
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specifiers. For more information on the data types supported by
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<productname>PostgreSQL</productname>, refer to <xref
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linkend="datatype">.
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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><literal>NOT NULL</></term>
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<listitem>
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<para>
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The column is not allowed to contain null values.
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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><literal>NULL</></term>
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<listitem>
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<para>
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The column is allowed to contain null values. This is the default.
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</para>
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<para>
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This clause is only provided for compatibility with
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non-standard SQL databases. Its use is discouraged in new
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applications.
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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><literal>DEFAULT
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<replaceable>default_expr</replaceable></literal></term>
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<listitem>
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<para>
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The <literal>DEFAULT</> clause assigns a default data value for
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the column whose column definition it appears within. The value
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is any variable-free expression (subqueries and cross-references
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to other columns in the current table are not allowed). The
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data type of the default expression must match the data type of the
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column.
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</para>
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<para>
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The default expression will be used in any insert operation that
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does not specify a value for the column. If there is no default
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for a column, then the default is null.
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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">server_name</replaceable></term>
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<listitem>
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<para>
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The name of an existing foreign server to use for the foreign table.
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For details on defining a server, see <xref
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linkend="SQL-CREATESERVER">.
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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><literal>OPTIONS ( <replaceable class="PARAMETER">option</replaceable> '<replaceable class="PARAMETER">value</replaceable>' [, ...] )</literal></term>
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<listitem>
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<para>
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Options to be associated with the new foreign table or one of its
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columns.
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The allowed option names and values are specific to each foreign
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data wrapper and are validated using the foreign-data wrapper's
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validator function. Duplicate option names are not allowed (although
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it's OK for a table option and a column option to have the same name).
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1 id="SQL-CREATEFOREIGNTABLE-examples">
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<title>Examples</title>
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<para>
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Create foreign table <structname>films</>, which will be accessed through
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the server <structname>film_server</>:
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<programlisting>
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CREATE FOREIGN TABLE films (
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code char(5) NOT NULL,
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title varchar(40) NOT NULL,
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did integer NOT NULL,
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date_prod date,
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kind varchar(10),
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len interval hour to minute
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)
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SERVER film_server;
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</programlisting></para>
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</refsect1>
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<refsect1 id="SQL-CREATEFOREIGNTABLE-compatibility">
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<title id="SQL-CREATEFOREIGNTABLE-compatibility-title">Compatibility</title>
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<para>
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The <command>CREATE FOREIGN TABLE</command> command largely conforms to the
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<acronym>SQL</acronym> standard; however, much as with
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<link linkend="sql-createtable"><command>CREATE TABLE</></link>,
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<literal>NULL</> constraints and zero-column foreign tables are permitted.
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The ability to specify a default value is also a <productname>PostgreSQL</>
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extension.
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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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<simplelist type="inline">
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<member><xref linkend="sql-alterforeigntable"></member>
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<member><xref linkend="sql-dropforeigntable"></member>
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<member><xref linkend="sql-createtable"></member>
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<member><xref linkend="sql-createserver"></member>
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</simplelist>
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</refsect1>
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</refentry>
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