using <xref linkend="sql-importforeignschema">. This command creates

foreign table definitions on the local server that match tables or

views present on the remote server. If the remote tables to be imported

have columns of user-defined data types, the local server must have types

of the same names.

have columns of user-defined data types, the local server must have

compatible typesof the same names.

</para>

<para>

<para>

Note that constraints other than <literal>NOT NULL</> will never be

imported from the remote tables, since <productname>PostgreSQL</>

does not support any other type of constraint on a foreign table.

Checking other types of constraints is always left to the remote server.

imported from the remote tables. Although <productname>PostgreSQL</>

does support <literal>CHECK</> constraints on foreign tables, there is no

provision for importing them automatically, because of the risk that a

constraint expression could evaluate differently on the local and remote

servers. Any such inconsistency in the behavior of a <literal>CHECK</>

constraint could lead to hard-to-detect errors in query optimization.

So if you wish to import <literal>CHECK</> constraints, you must do so

manually, and you should verify the semantics of each one carefully.

For more detail about the treatment of <literal>CHECK</> constraints on

foreign tables, see <xref linkend="sql-createforeigntable">.

</para>

</sect3>

</sect2>