@@ -2670,19 +2670,6 @@ P <optional> <replaceable>years</replaceable>-<replaceable>months</replaceable>-
26702670 to each field if any field is negative.
26712671 </para>
26722672
2673- <para>
2674- Internally <type>interval</type> values are stored as months, days,
2675- and seconds. This is done because the number of days in a month
2676- varies, and a day can have 23 or 25 hours if a daylight savings
2677- time adjustment is involved. The months and days fields are integers
2678- while the seconds field can store fractions. Because intervals are
2679- usually created from constant strings or <type>timestamp</type> subtraction,
2680- this storage method works well in most cases. Functions
2681- <function>justify_days</function> and <function>justify_hours</function> are
2682- available for adjusting days and hours that overflow their normal
2683- ranges.
2684- </para>
2685-
26862673 <para>
26872674 In the verbose input format, and in some fields of the more compact
26882675 input formats, field values can have fractional parts; for example
@@ -2734,6 +2721,33 @@ P <optional> <replaceable>years</replaceable>-<replaceable>months</replaceable>-
27342721 </tgroup>
27352722 </table>
27362723
2724+ <para>
2725+ Internally <type>interval</type> values are stored as months, days,
2726+ and seconds. This is done because the number of days in a month
2727+ varies, and a day can have 23 or 25 hours if a daylight savings
2728+ time adjustment is involved. The months and days fields are integers
2729+ while the seconds field can store fractions. Because intervals are
2730+ usually created from constant strings or <type>timestamp</type> subtraction,
2731+ this storage method works well in most cases, but can cause unexpected
2732+ results:
2733+
2734+ <programlisting>
2735+ SELECT EXTRACT(hours from '80 minutes'::interval);
2736+ date_part
2737+ -----------
2738+ 1
2739+
2740+ SELECT EXTRACT(days from '80 hours'::interval);
2741+ date_part
2742+ -----------
2743+ 0
2744+ </programlisting>
2745+
2746+ Functions <function>justify_days</function> and
2747+ <function>justify_hours</function> are available for adjusting days
2748+ and hours that overflow their normal ranges.
2749+ </para>
2750+
27372751 </sect2>
27382752
27392753 <sect2 id="datatype-interval-output">