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| -rw-r--r-- | doc/src/sgml/datatype.sgml | 21 |
1 files changed, 17 insertions, 4 deletions
diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml index 10da67ef5c6..d26fdc5fde6 100644 --- a/doc/src/sgml/datatype.sgml +++ b/doc/src/sgml/datatype.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/datatype.sgml,v 1.232 2008/11/09 00:28:34 tgl Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/datatype.sgml,v 1.233 2008/11/09 17:09:48 tgl Exp $ --> <chapter id="datatype"> <title id="datatype-title">Data Types</title> @@ -2413,13 +2413,26 @@ January 8 04:05:06 1999 PST Internally <type>interval</> values are stored as months, days, and seconds. This is done because the number of days in a month varies, and a day can have 23 or 25 hours if a daylight savings - time adjustment is involved. Because intervals are usually created - from constant strings or <type>timestamp</> subtraction, this - storage method works well in most cases. Functions + time adjustment is involved. The months and days fields are integers + while the seconds field can store fractions. Because intervals are + usually created from constant strings or <type>timestamp</> subtraction, + this storage method works well in most cases. Functions <function>justify_days</> and <function>justify_hours</> are available for adjusting days and hours that overflow their normal ranges. </para> + + <para> + In the verbose input format, and in some fields of the more compact + input formats, field values can have fractional parts; for example + <literal>'1.5 week'</> or <literal>'01:02:03.45'</>. Such input is + converted to the appropriate number of months, days, and seconds + for storage. When this would result in a fractional number of + months or days, the fraction is added to the lower-order fields + using the conversion factors 1 month = 30 days and 1 day = 24 hours. + For example, <literal>'1.5 month'</> becomes 1 month and 15 days. + Only seconds will ever be shown as fractional on output. + </para> </sect2> <sect2 id="datatype-interval-output"> |