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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/alter_foreign_table.sgml Normal file
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<!--
doc/src/sgml/rel/alter_foreign_table.sgml
PostgreSQL documentation
-->
<refentry id="SQL-ALTERFOREIGNTABLE">
<refmeta>
<refentrytitle>ALTER FOREIGN TABLE</refentrytitle>
<manvolnum>7</manvolnum>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>ALTER FOREIGN TABLE</refname>
<refpurpose>change the definition of a foreign table</refpurpose>
</refnamediv>
<indexterm zone="sql-alterforeigntable">
<primary>ALTER FOREIGN TABLE</primary>
</indexterm>
<refsynopsisdiv>
<synopsis>
ALTER FOREIGN TABLE <replaceable class="PARAMETER">name</replaceable>
<replaceable class="PARAMETER">action</replaceable> [, ... ]
ALTER FOREIGN TABLE <replaceable class="PARAMETER">name</replaceable>
RENAME [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> TO <replaceable class="PARAMETER">new_column</replaceable>
ALTER FOREIGN TABLE <replaceable class="PARAMETER">name</replaceable>
RENAME TO <replaceable class="PARAMETER">new_name</replaceable>
ALTER FOREIGN TABLE <replaceable class="PARAMETER">name</replaceable>
SET SCHEMA <replaceable class="PARAMETER">new_schema</replaceable>
<phrase>where <replaceable class="PARAMETER">action</replaceable> is one of:</phrase>
ADD [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> <replaceable class="PARAMETER">type</replaceable>
DROP [ COLUMN ] [ IF EXISTS ] <replaceable class="PARAMETER">column</replaceable> [ RESTRICT | CASCADE ]
ALTER [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> [ SET DATA ] TYPE <replaceable class="PARAMETER">type</replaceable>
ALTER [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> { SET | DROP } NOT NULL
OWNER TO <replaceable class="PARAMETER">new_owner</replaceable>
OPTIONS ( [ ADD | SET | DROP ] <replaceable class="PARAMETER">option</replaceable> ['<replaceable class="PARAMETER">value</replaceable>'] [, ... ])
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>ALTER FOREIGN TABLE</command> changes the definition of an
existing foreign table. There are several subforms:
<variablelist>
<varlistentry>
<term><literal>ADD COLUMN</literal></term>
<listitem>
<para>
This form adds a new column to the foreign table, using the same syntax as
<xref linkend="SQL-CREATEFOREIGNTABLE">.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>DROP COLUMN [ IF EXISTS ]</literal></term>
<listitem>
<para>
This form drops a column from a foreign table.
You will need to say <literal>CASCADE</> if
anything outside the table depends on the column; for example,
views.
If <literal>IF EXISTS</literal> is specified and the column
does not exist, no error is thrown. In this case a notice
is issued instead.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>SET DATA TYPE</literal></term>
<listitem>
<para>
This form changes the type of a column of a foreign table.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>SET</literal>/<literal>DROP NOT NULL</literal></term>
<listitem>
<para>
Mark a column as allowing, or not allowing, null values.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>OWNER</literal></term>
<listitem>
<para>
This form changes the owner of the foreign table to the
specified user.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>RENAME</literal></term>
<listitem>
<para>
The <literal>RENAME</literal> forms change the name of a foreign table
or the name of an individual column in a foreign table.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>SET SCHEMA</literal></term>
<listitem>
<para>
This form moves the foreign table into another schema.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>OPTIONS ( [ ADD | SET | DROP ] <replaceable class="PARAMETER">option</replaceable> ['<replaceable class="PARAMETER">value</replaceable>'] [, ... ] )</literal></term>
<listitem>
<para>
Change options for the foreign table or the column of the foreign table.
<literal>ADD</>, <literal>SET</>, and <literal>DROP</>
specify the action to be performed. <literal>ADD</> is assumed
if no operation is explicitly specified. Option names must be
unique; names and values are also validated using the foreign
data wrapper library.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
<para>
All the actions except <literal>RENAME</literal> and <literal>SET SCHEMA</>
can be combined into
a list of multiple alterations to apply in parallel. For example, it
is possible to add several columns and/or alter the type of several
columns in a single command.
</para>
<para>
You must own the table to use <command>ALTER FOREIGN TABLE</>.
To change the schema of a foreign table, you must also have
<literal>CREATE</literal> privilege on the new schema.
To add the table as a new child of a parent table, you must own the
parent table as well.
To alter the owner, you must also be a direct or indirect member of the new
owning role, and that role must have <literal>CREATE</literal> privilege on
the table's schema. (These restrictions enforce that altering the owner
doesn't do anything you couldn't do by dropping and recreating the table.
However, a superuser can alter ownership of any table anyway.)
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><replaceable class="PARAMETER">name</replaceable></term>
<listitem>
<para>
The name (possibly schema-qualified) of an existing foreign table to
alter.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">column</replaceable></term>
<listitem>
<para>
Name of a new or existing column.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">new_column</replaceable></term>
<listitem>
<para>
New name for an existing column.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">new_name</replaceable></term>
<listitem>
<para>
New name for the table.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">type</replaceable></term>
<listitem>
<para>
Data type of the new column, or new data type for an existing
column.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>CASCADE</literal></term>
<listitem>
<para>
Automatically drop objects that depend on the dropped column
(for example, views referencing the column).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>RESTRICT</literal></term>
<listitem>
<para>
Refuse to drop the column if there are any dependent
objects. This is the default behavior.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">new_owner</replaceable></term>
<listitem>
<para>
The user name of the new owner of the table.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">new_schema</replaceable></term>
<listitem>
<para>
The name of the schema to which the table will be moved.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<para>
The key word <literal>COLUMN</literal> is noise and can be omitted.
</para>
<para>
Consistency with the foreign server is not checked when a column is
added or removed with <literal>ADD COLUMN</literal> or
<literal>DROP COLUMN</literal>, a system <literal>oid</> column is added
or removed, a <literal>CHECK</> or <literal>NOT NULL</> constraint is
added, or column type is changed with <literal>ALTER TYPE</>. It is the
user's responsibility to ensure that the table definition matches the
remote side.
</para>
<para>
Refer to <xref linkend="sql-createforeigntable"> for a further description of valid
parameters.
</para>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
To mark a column as not-null:
<programlisting>
ALTER FOREIGN TABLE distributors ALTER COLUMN street SET NOT NULL;
</programlisting>
</para>
<para>
To change options of a foreign table:
<programlisting>
ALTER FOREIGN TABLE myschema.distributors OPTIONS (ADD opt1 'value', SET opt2, 'value2', DROP opt3 'value3');
</programlisting>
</para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
The forms <literal>ADD</literal>, <literal>DROP</>,
and <literal>SET DATA TYPE</literal>
conform with the SQL standard. The other forms are
<productname>PostgreSQL</productname> extensions of the SQL standard.
Also, the ability to specify more than one manipulation in a single
<command>ALTER FOREIGN TABLE</> command is an extension.
</para>
<para>
<command>ALTER FOREIGN TABLE DROP COLUMN</> can be used to drop the only
column of a foreign table, leaving a zero-column table. This is an
extension of SQL, which disallows zero-column foreign tables.
</para>
</refsect1>
</refentry>