isn't
assumed to hold, but is only recorded for possible future use.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>VALIDATE CONSTRAINT</literal></term>
<listitem>
<para>
This form marks as valid a constraint that was previously marked
as <literal>NOT VALID</literal>. No action is taken to verify the
constraint, but future queries will assume that it holds.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>DROP CONSTRAINT [ IF EXISTS ]</literal></term>
<listitem>
<para>
This form drops the specified constraint on a foreign table.
If <literal>IF EXISTS</literal> is specified and the constraint
does not exist, no error is thrown.
In this case a notice is issued instead.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>DISABLE</literal>/<literal>ENABLE [ REPLICA | ALWAYS ] TRIGGER</literal></term>
<listitem>
<para>
These forms configure the firing of trigger(s) belonging to the foreign
table. See the similar form of <link linkend="sql-altertable"><command>ALTER TABLE</command></link> for more
details.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>SET WITHOUT OIDS</literal></term>
<listitem>
<para>
Backward compatibility syntax for removing the <literal>oid</literal>
system column. As <literal>oid</literal> system columns cannot be added
anymore, this never has an effect.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>INHERIT <replaceable class="parameter">parent_table</replaceable></literal></term>
<listitem>
<para>
This form adds the target foreign table as a new child of the specified
parent table.
See the similar form of <link linkend="sql-altertable"><command>ALTER TABLE</command></link>
for more details.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>NO INHERIT <replaceable class="parameter">parent_table</replaceable></literal></term>
<listitem>
<para>
This form removes the target foreign table from the list of children of
the specified parent table.
</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>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 one of its columns.
<literal>ADD</literal>, <literal>SET</literal>, and <literal>DROP</literal>
specify the action to be performed. <literal>ADD</literal> is assumed
if no operation is explicitly specified. Duplicate option names are not
allowed (although it's OK for a table option and a column option to have
the same name). Option names and values are also validated using the
foreign data wrapper library.
</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>
</variablelist>
</para>
<para>
All the actions except <literal>RENAME</literal> and <literal>SET SCHEMA</literal>
can be combined into
a list of multiple alterations to apply