foreign tables using the wrapper.

The validator function must be registered as taking two arguments, a

text array containing the options to be validated, and an OID

representing the type of object the options are associated with (in

the form of the OID of the system catalog the object would be stored

in, either

<literal>ForeignDataWrapperRelationId</literal>,

<literal>ForeignServerRelationId</literal>,

<literal>UserMappingRelationId</literal>,

or <literal>ForeignTableRelationId</literal>).

representing the type of object the options are associated with. The

latter corresponds to the OID of the system catalog the object

would be stored in, one of:

<itemizedlist spacing="compact">

<listitem><para><literal>AttributeRelationId</literal></para></listitem>

<listitem><para><literal>ForeignDataWrapperRelationId</literal></para></listitem>

<listitem><para><literal>ForeignServerRelationId</literal></para></listitem>

<listitem><para><literal>ForeignTableRelationId</literal></para></listitem>

<listitem><para><literal>UserMappingRelationId</literal></para></listitem>

</itemizedlist>

If no validator function is supplied, options are not checked at object

creation time or object alteration time.

</para>