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Basic foreign table support.

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Foreign tables are a core component of SQL/MED.  This commit does
not provide a working SQL/MED infrastructure, because foreign tables
cannot yet be queried.  Support for foreign table scans will need to
be added in a future patch.  However, this patch creates the necessary
system catalog structure, syntax support, and support for ancillary
operations such as COMMENT and SECURITY LABEL.

Shigeru Hanada, heavily revised by Robert Haas
This commit is contained in:
Robert Haas
2011-01-01 23:48:11 -05:00
parent 6600d5e91c
commit 0d692a0dc9
69 changed files with 2275 additions and 211 deletions
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doc/src/sgml/ref/create_foreign_table.sgml Normal file
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<!-- doc/src/sgml/ref/create_foreign_table.sgml -->
<refentry id="SQL-CREATEFOREIGNTABLE">
<refmeta>
<refentrytitle>CREATE FOREIGN TABLE</refentrytitle>
<manvolnum>7</manvolnum>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>CREATE FOREIGN TABLE</refname>
<refpurpose>define a new foreign table</refpurpose>
</refnamediv>
<indexterm zone="sql-createforeigntable">
<primary>CREATE FOREIGN TABLE</primary>
</indexterm>
<refsynopsisdiv>
<synopsis>
CREATE FOREIGN TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name</replaceable> ( [
{ <replaceable class="PARAMETER">column_name</replaceable> <replaceable class="PARAMETER">data_type</replaceable> [ NULL | NOT NULL ] }
[, ... ]
] )
SERVER <replaceable class="parameter">server_name</replaceable>
[ OPTIONS ( <replaceable class="PARAMETER">option</replaceable> '<replaceable class="PARAMETER">value</replaceable>' [, ... ] ) ]
</synopsis>
</refsynopsisdiv>
<refsect1 id="SQL-CREATEFOREIGNTABLE-description">
<title>Description</title>
<para>
<command>CREATE FOREIGN TABLE</command> will create a new foreign table
in the current database. The table will be owned by the user issuing the
command.
</para>
<para>
If a schema name is given (for example, <literal>CREATE FOREIGN TABLE
myschema.mytable ...</>) then the table is created in the specified
schema. Otherwise it is created in the current schema.
The name of the foreign table must be
distinct from the name of any other foreign table, table, sequence, index,
or view in the same schema.
</para>
<para>
<command>CREATE FOREIGN TABLE</command> also automatically creates a data
type that represents the composite type corresponding to one row of
the foreign table. Therefore, foreign tables cannot have the same
name as any existing data type in the same schema.
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><literal>IF NOT EXISTS</></term>
<listitem>
<para>
Do not throw an error if a relation with the same name already exists.
A notice is issued in this case. Note that there is no guarantee that
the existing relation is anything like the one that would have been
created.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">table_name</replaceable></term>
<listitem>
<para>
The name (optionally schema-qualified) of the table to be created.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">column_name</replaceable></term>
<listitem>
<para>
The name of a column to be created in the new table.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">data_type</replaceable></term>
<listitem>
<para>
The data type of the column. This can include array
specifiers. For more information on the data types supported by
<productname>PostgreSQL</productname>, refer to <xref
linkend="datatype">.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>NOT NULL</></term>
<listitem>
<para>
The column is not allowed to contain null values.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>NULL</></term>
<listitem>
<para>
The column is allowed to contain null values. This is the default.
</para>
<para>
This clause is only provided for compatibility with
non-standard SQL databases. Its use is discouraged in new
applications.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>OPTIONS ( <replaceable class="PARAMETER">option</replaceable> = '<replaceable class="PARAMETER">value</replaceable>' [, ...] )</literal></term>
<listitem>
<para>
Options to be associated with the new foreign table.
The allowed option names and values are specific to each foreign
data wrapper and are validated using the foreign-data wrapper
library. Option names must be unique.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id="SQL-CREATEFOREIGNTABLE-examples">
<title>Examples</title>
<para>
Create foreign table <structname>films</> with <structname>film_server</>:
<programlisting>
CREATE FOREIGN TABLE films (
code char(5) NOT NULL,
title varchar(40) NOT NULL,
did integer NOT NULL,
date_prod date,
kind varchar(10),
len interval hour to minute
)
SERVER film_server;
</programlisting>
</para>
</refsect1>
<refsect1 id="SQL-CREATEFOREIGNTABLE-compatibility">
<title id="SQL-CREATEFOREIGNTABLE-compatibility-title">Compatibility</title>
<para>
The <command>CREATE FOREIGN TABLE</command> command largely conforms to the
<acronym>SQL</acronym> standard; however, much as with
<link linkend="sql-createtable"><command>CREATE TABLE</></link>,
<literal>NULL</> constraints and zero-column foreign tables are permitted.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="sql-alterforeigntable"></member>
<member><xref linkend="sql-dropforeigntable"></member>
<member><xref linkend="sql-createtable"></member>
<member><xref linkend="sql-createserver"></member>
</simplelist>
</refsect1>
</refentry>