Interval->day docs and regression tests

Please find attached diffs for documentation and simple regression
tests for the new interval->day changes. I added tests for
justify_hours() and justify_days() to interval.sql, as they take
interval input and produce interval output. If there's a more
appropriate place for them, please let me know.

I've included the diff in the email as well (below) for ease of review.

Michael Glaesemann
grzm myrealbox com

Index: doc/src/sgml/func.sgml
===================================================================
RCS file: /projects/cvsroot/pgsql/doc/src/sgml/func.sgml,v
retrieving revision 1.269
diff -c -r1.269 func.sgml
*** doc/src/sgml/func.sgml 22 Jul 2005 21:16:14 -0000 1.269
--- doc/src/sgml/func.sgml 26 Jul 2005 00:43:49 -0000
***************
*** 4903,4908 ****
--- 4903,4926 ----
such pair.
</para>

+ <para>
+ When adding an <type>interval</type> value to (or subtracting an
+ <type>interval</type> value from) a <type>timestamp with time
zone</type>
+ value, the days component advances (or decrements) the date of the
+ <type>timestamp with time zone<type> by the indicated number of
days.
+ Across daylight saving time changes (with the session tiem zone
set to a
+ time zone that recognizes DST), this means <literal>interval '1
day'</literal>
+ does not necessarily equal <literal>interval '24 hours'</literal>.
+ For example, with the session time zone set to <literal>CST7CDT</
literal>
+ <literal>timestamp with time zone '2005-04-02 12:00-07' +
interval '1 day' </literal>
+ will produce <literal>timestamp with time zone '2005-04-03
12:00-06'</literal>,
+ while adding <literal>interval '24 hours'</literal> to the same
initial
+ <type>timestamp with time zone</type> produces
+ <literal>timestamp with time zone '2005-04-03 13:00-06'</
literal>, as there is
+ a change in daylight saving time at <literal>2005-04-03 02:00</
literal> in time zone
+ <literal>CST7CDT</literal>.
+ </para>
+
<table id="operators-datetime-table">
<title>Date/Time Operators</title>

Index: src/test/regress/expected/horology.out
===================================================================
RCS file: /projects/cvsroot/pgsql/src/test/regress/expected/
horology.out,v
retrieving revision 1.56
diff -c -r1.56 horology.out
*** src/test/regress/expected/horology.out 27 May 2005 21:31:23
-0000 1.56
--- src/test/regress/expected/horology.out 26 Jul 2005 00:43:49 -0000
***************
*** 598,603 ****
--- 598,630 ----
t
(1 row)

+ -- timestamp with time zone, interval arithmetic around DST change
+ SET TIME ZONE 'CST7CDT';
+ SELECT timestamp with time zone '2005-04-02 12:00-07' + interval '1
day' as "Apr 3, 12:00";
+ Apr 3, 12:00
+ ------------------------------
+ Sun Apr 03 12:00:00 2005 CDT
+ (1 row)
+
+ SELECT timestamp with time zone '2005-04-02 12:00-07' + interval
'24 hours' as "Apr 3, 13:00";
+ Apr 3, 13:00
+ ------------------------------
+ Sun Apr 03 13:00:00 2005 CDT
+ (1 row)
+
+ SELECT timestamp with time zone '2005-04-03 12:00-06' - interval '1
day' as "Apr 2, 12:00";
+ Apr 2, 12:00
+ ------------------------------
+ Sat Apr 02 12:00:00 2005 CST
+ (1 row)
+
+ SELECT timestamp with time zone '2005-04-03 12:00-06' - interval
'24 hours' as "Apr 2, 11:00";
+ Apr 2, 11:00
+ ------------------------------
+ Sat Apr 02 11:00:00 2005 CST
+ (1 row)
+
+ RESET TIME ZONE;
SELECT timestamptz(date '1994-01-01', time '11:00') AS
"Jan_01_1994_10am";
Jan_01_1994_10am
------------------------------
Index: src/test/regress/expected/interval.out
===================================================================
RCS file: /projects/cvsroot/pgsql/src/test/regress/expected/
interval.out,v
retrieving revision 1.12
diff -c -r1.12 interval.out
*** src/test/regress/expected/interval.out 20 Jul 2005 16:42:32
-0000 1.12
--- src/test/regress/expected/interval.out 26 Jul 2005 00:43:49 -0000
***************
*** 228,230 ****
--- 228,243 ----
@ 4541 years 4 mons 4 days 17 mins 31 secs
(1 row)

+ -- test justify_hours() and justify_days()
+ SELECT justify_hours(interval '6 months 3 days 52 hours 3 minutes 2
seconds') as "6 mons 5 days 4 hours 3 mins 2 seconds";
+ 6 mons 5 days 4 hours 3 mins 2 seconds
+ ----------------------------------------
+ @ 6 mons 5 days 4 hours 3 mins 2 secs
+ (1 row)
+
+ SELECT justify_days(interval '6 months 36 days 5 hours 4 minutes 3
seconds') as "7 mons 6 days 5 hours 4 mins 3 seconds";
+ 7 mons 6 days 5 hours 4 mins 3 seconds
+ ----------------------------------------
+ @ 7 mons 6 days 5 hours 4 mins 3 secs
+ (1 row)
+
Index: src/test/regress/sql/horology.sql
===================================================================
RCS file: /projects/cvsroot/pgsql/src/test/regress/sql/horology.sql,v
retrieving revision 1.30
diff -c -r1.30 horology.sql
*** src/test/regress/sql/horology.sql 7 Apr 2005 01:51:41 -0000
1.30
--- src/test/regress/sql/horology.sql 26 Jul 2005 00:43:49 -0000
***************
*** 114,119 ****
--- 114,128 ----
SELECT (timestamp with time zone 'tomorrow' = (timestamp with time
zone 'yesterday' + interval '2 days')) as "True";
SELECT (timestamp with time zone 'tomorrow' > 'now') as "True";

+ -- timestamp with time zone, interval arithmetic around DST change
+ SET TIME ZONE 'CST7CDT';
+ SELECT timestamp with time zone '2005-04-02 12:00-07' + interval '1
day' as "Apr 3, 12:00";
+ SELECT timestamp with time zone '2005-04-02 12:00-07' + interval
'24 hours' as "Apr 3, 13:00";
+ SELECT timestamp with time zone '2005-04-03 12:00-06' - interval '1
day' as "Apr 2, 12:00";
+ SELECT timestamp with time zone '2005-04-03 12:00-06' - interval
'24 hours' as "Apr 2, 11:00";
+ RESET TIME ZONE;
+
+
SELECT timestamptz(date '1994-01-01', time '11:00') AS
"Jan_01_1994_10am";
SELECT timestamptz(date '1994-01-01', time '10:00') AS
"Jan_01_1994_9am";
SELECT timestamptz(date '1994-01-01', time with time zone
'11:00-8') AS "Jan_01_1994_11am";
Index: src/test/regress/sql/interval.sql
===================================================================
RCS file: /projects/cvsroot/pgsql/src/test/regress/sql/interval.sql,v
retrieving revision 1.7
diff -c -r1.7 interval.sql
*** src/test/regress/sql/interval.sql 26 May 2005 02:04:14
-0000 1.7
--- src/test/regress/sql/interval.sql 26 Jul 2005 00:43:49 -0000
***************
*** 69,71 ****
--- 69,78 ----

-- test long interval input
select '4 millenniums 5 centuries 4 decades 1 year 4 months 4 days
17 minutes 31 seconds'::interval;
+
+
+ -- test justify_hours() and justify_days()
+
+ SELECT justify_hours(interval '6 months 3 days 52 hours 3 minutes 2
seconds') as "6 mons 5 days 4 hours 3 mins 2 seconds";
+ SELECT justify_days(interval '6 months 36 days 5 hours 4 minutes 3
seconds') as "7 mons 6 days 5 hours 4 mins 3 seconds";
+