Re: Odd behaviour of timestamptz

Matteo Beccati <php@beccati.com> writes:
> test=# INSERT into test values ('1910-01-10');
> INSERT 0 1

> test=# INSERT into test values ('1990-01-10');
> INSERT 0 1

> test=# SELECT * from test;
>            data
> ----------------------------
> 1910-01-10 00:00:00+00:19:32
> 1990-01-10 00:00:00+01
> (2 rows)

I'll bet you are running in Europe/Amsterdam time zone?  The above is
correct behavior according to the zic data files (see below).

            regards, tom lane


# Netherlands

# Howse writes that the Netherlands' railways used GMT between 1892 and 1940,
# but for other purposes the Netherlands used Amsterdam mean time.

# However, Robert H. van Gent writes (2001-04-01):
# Howse's statement is only correct up to 1909. From 1909-05-01 (00:00:00
# Amsterdam mean time) onwards, the whole of the Netherlands (including
# the Dutch railways) was required by law to observe Amsterdam mean time
# (19 minutes 32.13 seconds ahead of GMT). This had already been the
# common practice (except for the railways) for many decades but it was
# not until 1909 when the Dutch government finally defined this by law.
# On 1937-07-01 this was changed to 20 minutes (exactly) ahead of GMT and
# was generally known as Dutch Time ("Nederlandse Tijd").
#
# (2001-04-08):
# 1892-05-01 was the date when the Dutch railways were by law required to
# observe GMT while the remainder of the Netherlands adhered to the common
# practice of following Amsterdam mean time.
#
# (2001-04-09):
# In 1835 the authorities of the province of North Holland requested the
# municipal authorities of the towns and cities in the province to observe
# Amsterdam mean time but I do not know in how many cases this request was
# actually followed.
#
# From 1852 onwards the Dutch telegraph offices were by law required to
# observe Amsterdam mean time. As the time signals from the observatory of
# Leiden were also distributed by the telegraph system, I assume that most
# places linked up with the telegraph (and railway) system automatically
# adopted Amsterdam mean time.
#
# Although the early Dutch railway companies initially observed a variety
# of times, most of them had adopted Amsterdam mean time by 1858 but it
# was not until 1866 when they were all required by law to observe
# Amsterdam mean time.

# The data before 1945 are taken from
# <http://www.phys.uu.nl/~vgent/wettijd/wettijd.htm>.

# Rule    NAME    FROM    TO    TYPE    IN    ON    AT    SAVE    LETTER/S
Rule    Neth    1916    only    -    May     1    0:00    1:00    NST    # Netherlands Summer Time
Rule    Neth    1916    only    -    Oct     1    0:00    0    AMT    # Amsterdam Mean Time
Rule    Neth    1917    only    -    Apr    16    2:00s    1:00    NST
Rule    Neth    1917    only    -    Sep    17    2:00s    0    AMT
Rule    Neth    1918    1921    -    Apr    Mon>=1    2:00s    1:00    NST
Rule    Neth    1918    1921    -    Sep    lastMon    2:00s    0    AMT
Rule    Neth    1922    only    -    Mar    lastSun    2:00s    1:00    NST
Rule    Neth    1922    1936    -    Oct    Sun>=2    2:00s    0    AMT
Rule    Neth    1923    only    -    Jun    Fri>=1    2:00s    1:00    NST
Rule    Neth    1924    only    -    Mar    lastSun    2:00s    1:00    NST
Rule    Neth    1925    only    -    Jun    Fri>=1    2:00s    1:00    NST
# From 1926 through 1939 DST began 05-15, except that it was delayed by a week
# in years when 05-15 fell in the Pentecost weekend.
Rule    Neth    1926    1931    -    May    15    2:00s    1:00    NST
Rule    Neth    1932    only    -    May    22    2:00s    1:00    NST
Rule    Neth    1933    1936    -    May    15    2:00s    1:00    NST
Rule    Neth    1937    only    -    May    22    2:00s    1:00    NST
Rule    Neth    1937    only    -    Jul     1    0:00    1:00    S
Rule    Neth    1937    1939    -    Oct    Sun>=2    2:00s    0    -
Rule    Neth    1938    1939    -    May    15    2:00s    1:00    S
Rule    Neth    1945    only    -    Apr     2    2:00s    1:00    S
Rule    Neth    1945    only    -    Sep    16    2:00s    0    -
#
# Amsterdam Mean Time was +00:19:32.13 exactly, but the .13 is omitted
# below because the current format requires GMTOFF to be an integer.
# Zone    NAME        GMTOFF    RULES    FORMAT    [UNTIL]
Zone Europe/Amsterdam    0:19:32 -    LMT    1835
            0:19:32    Neth    %s    1937 Jul  1
            0:20    Neth    NE%sT    1940 May 16 0:00 # Dutch Time
            1:00    C-Eur    CE%sT    1945 Apr  2 2:00
            1:00    Neth    CE%sT    1977
            1:00    EU    CE%sT