class="parameter">tablename</replaceable>_<replaceable class="parameter">colname</replaceable>_seq OWNED BY <replaceable class="parameter">tablename</replaceable>.<replaceable class="parameter">colname</replaceable>;
</programlisting>

     Thus, we have created an integer column and arranged for its default
     values to be assigned from a sequence generator.  A <literal>NOT NULL</literal>
     constraint is applied to ensure that a null value cannot be
     inserted.  (In most cases you would also want to attach a
     <literal>UNIQUE</literal> or <literal>PRIMARY KEY</literal> constraint to prevent
     duplicate values from being inserted by accident, but this is
     not automatic.)  Lastly, the sequence is marked as <quote>owned by</quote>
     the column, so that it will be dropped if the column or table is dropped.
    </para>

    <note>
      <para>
        Because <type>smallserial</type>, <type>serial</type> and
        <type>bigserial</type> are implemented using sequences, there may
        be "holes" or gaps in the sequence of values which appears in the
        column, even if no rows are ever deleted.  A value allocated
        from the sequence is still "used up" even if a row containing that
        value is never successfully inserted into the table column.  This
        may happen, for example, if the inserting transaction rolls back.
        See <literal>nextval()</literal> in <xref linkend="functions-sequence"/>
        for details.
      </para>
    </note>

    <para>
     To insert the next value of the sequence into the <type>serial</type>
     column, specify that the <type>serial</type>
     column should be assigned its default value. This can be done
     either by excluding the column from the list of columns in
     the <command>INSERT</command> statement, or through the use of
     the <literal>DEFAULT</literal> key word.
    </para>

    <para>
     The type names <type>serial</type> and <type>serial4</type> are
     equivalent: both create <type>integer</type> columns.  The type
     names <type>bigserial</type> and <type>serial8</type> work
     the same way, except that they create a <type>bigint</type>
     column.  <type>bigserial</type> should be used if you anticipate
     the use of more than 2<superscript>31</superscript> identifiers over the
     lifetime of the table. The type names <type>smallserial</type> and
     <type>serial2</type> also work the same way, except that they
     create a <type>smallint</type> column.
    </para>

    <para>
     The sequence created for a <type>serial</type> column is
     automatically dropped when the owning column is dropped.
     You can drop the sequence without dropping the column, but this
     will force removal of the column default expression.
    </para>
   </sect2>
  </sect1>

  <sect1 id="datatype-money">
   <title>Monetary Types</title>

   <para>
    The <type>money</type> type stores a currency amount with a fixed
    fractional precision; see <xref
    linkend="datatype-money-table"/>.  The fractional precision is
    determined by the database's <xref linkend="guc-lc-monetary"/> setting.
    The range shown in the table assumes there are two fractional digits.
    Input is accepted in a variety of formats, including integer and
    floating-point literals, as well as typical
    currency formatting, such as <literal>'$1,000.00'</literal>.
    Output is generally in the latter form but depends on the locale.
   </para>

    <table id="datatype-money-table">
     <title>Monetary Types</title>
     <tgroup cols="4">
      <colspec colname="col1" colwidth="2*"/>
      <colspec colname="col2" colwidth="1*"/>
      <colspec colname="col3" colwidth="2*"/>
      <colspec colname="col4" colwidth="2*"/>
      <thead>
       <row>
        <entry>Name</entry>
        <entry>Storage Size</entry>
        <entry>Description</entry>
        <entry>Range</entry>
       </row>
      </thead>
      <tbody>
       <row>
        <entry><type>money</type></entry>