Back-patch commit 1c1a7cbd6a1600c9, along with subsequent portability
fixes, into all active branches. Also, back-patch commits 696027727 and
596857043 (addition of zic -P option) into 9.1 and 9.2, just to reduce
differences between the branches. src/timezone/ is now largely identical
in all active branches, except that in 9.1, pgtz.c retains the
initial-timezone-selection code that was moved over to initdb in 9.2.
Ordinarily we wouldn't risk this much code churn in back branches, but it
seems necessary in this case, because among the changes are two feature
additions in the "zic" zone data file compiler (a larger limit on the
number of allowed DST transitions, and addition of a "%z" escape in zone
abbreviations). IANA have not yet started to use those features in their
tzdata files, but presumably they will before too long. If we don't update
then we'll be unable to adopt new timezone data. Also, installations built
with --with-system-tzdata (which includes most distro-supplied builds, I
believe) might fail even if we don't update our copies of the data files.
There are assorted bug fixes too, mostly affecting obscure timezones or
post-2037 dates.
Discussion: <13601.1468868947@sss.pgh.pa.us>
We really need to sync all of our IANA-derived timezone code with upstream,
but that's going to be a large patch and I certainly don't care to shove
such a thing into stable branches immediately before a release. As a
stopgap, copy just the tzcode2016c logic that checks validity of timezone
abbreviations. This prevents getting multiple "time zone abbreviation
differs from POSIX standard" bleats with tzdata 2014b and later.
Up to now, PG has assumed that any given timezone abbreviation (such as
"EDT") represents a constant GMT offset in the usage of any particular
region; we had a way to configure what that offset was, but not for it
to be changeable over time. But, as with most things horological, this
view of the world is too simplistic: there are numerous regions that have
at one time or another switched to a different GMT offset but kept using
the same timezone abbreviation. Almost the entire Russian Federation did
that a few years ago, and later this month they're going to do it again.
And there are similar examples all over the world.
To cope with this, invent the notion of a "dynamic timezone abbreviation",
which is one that is referenced to a particular underlying timezone
(as defined in the IANA timezone database) and means whatever it currently
means in that zone. For zones that use or have used daylight-savings time,
the standard and DST abbreviations continue to have the property that you
can specify standard or DST time and get that time offset whether or not
DST was theoretically in effect at the time. However, the abbreviations
mean what they meant at the time in question (or most recently before that
time) rather than being absolutely fixed.
The standard abbreviation-list files have been changed to use this behavior
for abbreviations that have actually varied in meaning since 1970. The
old simple-numeric definitions are kept for abbreviations that have not
changed, since they are a bit faster to resolve.
While this is clearly a new feature, it seems necessary to back-patch it
into all active branches, because otherwise use of Russian zone
abbreviations is going to become even more problematic than it already was.
This change supersedes the changes in commit 513d06ded et al to modify the
fixed meanings of the Russian abbreviations; since we've not shipped that
yet, this will avoid an undesirably incompatible (not to mention incorrect)
change in behavior for timestamps between 2011 and 2014.
This patch makes some cosmetic changes in ecpglib to keep its usage of
datetime lookup tables as similar as possible to the backend code, but
doesn't do anything about the increasingly obsolete set of timezone
abbreviation definitions that are hard-wired into ecpglib. Whatever we
do about that will likely not be appropriate material for back-patching.
Also, a potential free() of a garbage pointer after an out-of-memory
failure in ecpglib has been fixed.
This patch also fixes pre-existing bugs in DetermineTimeZoneOffset() that
caused it to produce unexpected results near a timezone transition, if
both the "before" and "after" states are marked as standard time. We'd
only ever thought about or tested transitions between standard and DST
time, but that's not what's happening when a zone simply redefines their
base GMT offset.
In passing, update the SGML documentation to refer to the Olson/zoneinfo/
zic timezone database as the "IANA" database, since it's now being
maintained under the auspices of IANA.
The quick hack I added to zic to dump out currently-in-use timezone
abbreviations turns out to have a nasty bug: within each zone, it was
printing the last "struct ttinfo" to be *defined*, not necessarily the
last one in use. This was mainly a problem in zones that had changed the
meaning of their zone abbreviation (to another GMT offset value) and later
changed it back.
As a result of this error, we'd missed out updating the tznames/ files
for some jurisdictions that have changed their zone abbreviations since
the tznames/ files were originally created. I'll address the missing data
updates in a separate commit.
We used to have externs for getopt() and its API variables scattered
all over the place. Now that we find we're going to need to tweak the
variable declarations for Cygwin, it seems like a good idea to have
just one place to tweak.
In this commit, the variables are declared "#ifndef HAVE_GETOPT_H".
That may or may not work everywhere, but we'll soon find out.
Andres Freund
Add an option to zic.c to dump out all non-obsolete timezone abbreviations
defined in the Olson database. Comparing this list to its previous state
will clue us in when something happens that we may need to account for in
the tznames/ time zone abbreviation lists. The README file's previous
exhortation to "just grep for differences" was completely useless advice,
in my now-considerable experience; but maybe this will be a bit more
useful. As a starting point I built the same list from the tzdata files
as they existed in 2006, which is committed here as known_abbrevs.txt.
Comparison indeed turned up quite a few changes we had neglected to account
for, which I will commit separately.
Per C standard, these are semantically the same thing; but saying NULL
when you mean NULL is good for readability.
Marti Raudsepp, per results of INRIA's Coccinelle.
corner cases that come up in certain timezones (apparently, only those with
lots and lots of distinct TZ transition rules, as far as I can gather from
a quick scan of their archives). Per suggestion from Jeevan Chalke.
Back-patch to 8.4. Possibly we need to push this into earlier releases
as well, but I'm hesitant to update them to the 64-bit tzcode without
more thought and testing.
this adds support for 64-bit tzdata files, which is needed to support DST
calculations beyond 2038. Add a regression test case to give some minimal
confidence that that really works.
Heikki Linnakangas
Standard English uses "may", "can", and "might" in different ways:
may - permission, "You may borrow my rake."
can - ability, "I can lift that log."
might - possibility, "It might rain today."
Unfortunately, in conversational English, their use is often mixed, as
in, "You may use this variable to do X", when in fact, "can" is a better
choice. Similarly, "It may crash" is better stated, "It might crash".
suffix, to distinguish them from doubles. Make some function declarations
and definitions use the "const" qualifier for arguments consistently.
Ignore warning 4102 ("unreferenced label"), because such warnings
are always emitted by bison-generated code. Patch from Magnus Hagander.
example SET TIME ZONE 'america/new_york' works now. This seems a good
idea on general user-friendliness grounds, and is part of the solution
to the timestamp-input parsing problems I noted recently.
* Changes the APIs to the timezone functions to take a pg_tz pointer as
an argument, representing the timezone to use for the selected
operation.
* Adds a global_timezone variable that represents the current timezone
in the backend as set by SET TIMEZONE (or guc, or env, etc).
* Implements a hash-table cache of loaded tables, so we don't have to
read and parse the TZ file everytime we change a timezone. While not
necesasry now (we don't change timezones very often), I beleive this
will be necessary (or at least good) when "multiple timezones in the
same query" is eventually implemented. And code-wise, this was the time
to do it.
There are no user-visible changes at this time. Implementing the
"multiple zones in one query" is a later step...
This also gets rid of some of the cruft needed to "back out a timezone
change", since we previously couldn't check a timezone unless it was
activated first.
Passes regression tests on win32, linux (slackware 10) and solaris x86.
Magnus Hagander
it with previous prototype to suppress complaints from picky compilers,
per report from Scott Bailey. Also, remove substitute strerror
definition --- not needed, since we link this with libpgport.
place of time_t, as per prior discussion. The behavior does not change
on machines without a 64-bit-int type, but on machines with one, which
is most, we are rid of the bizarre boundary behavior at the edges of
the 32-bit-time_t range (1901 and 2038). The system will now treat
times over the full supported timestamp range as being in your local
time zone. It may seem a little bizarre to consider that times in
4000 BC are PST or EST, but this is surely at least as reasonable as
propagating Gregorian calendar rules back that far.
I did not modify the format of the zic timezone database files, which
means that for the moment the system will not know about daylight-savings
periods outside the range 1901-2038. Given the way the files are set up,
it's not a simple decision like 'widen to 64 bits'; we have to actually
think about the range of years that need to be supported. We should
probably inquire what the plans of the upstream zic people are before
making any decisions of our own.
and should do now that we control our own destiny for timezone handling,
but this commit gets the bulk of the picayune diffs in place.
Magnus Hagander and Tom Lane.
