comment line where output as too long, and update typedefs for /lib
directory. Also fix case where identifiers were used as variable names
in the backend, but as typedefs in ecpg (favor the backend for
indenting).
Backpatch to 8.1.X.
in the zic database or zone names found in the date token table. This
preserves the old ability to do AT TIME ZONE 'PST' along with the new
ability to do AT TIME ZONE 'PST8PDT'. Per gripe from Bricklen Anderson.
Also, fix some inconsistencies in usage of TZ_STRLEN_MAX --- the old
code had the potential for one-byte buffer overruns, though given
alignment considerations it's unlikely there was any real risk.
problems:
---------------------------------------------------------------------------
Support cross compilation by compiling "zic" with a native compiler.
This relies on the output of zic being platform independent, but that is
currently the case.
with a table that has a small predicted size. Avoids wasting several
hundred K on the timezone hash table, which is likely to have only one
or a few entries, but the entries use up 10Kb apiece ...
includes error checking and an appropriate ereport(ERROR) message.
This gets rid of rather tedious and error-prone manipulation of errno,
as well as a Windows-specific bug workaround, at more than a dozen
call sites. After an idea in a recent patch by Heikki Linnakangas.
"AT TIME ZONE", and not just the shorlist previously available. For
example:
SELECT CURRENT_TIMESTAMP AT TIME ZONE 'Europe/London';
works fine now. It will also obey whatever DST rules were in effect at
just that date, which the previous implementation did not.
It also supports the AT TIME ZONE on the timetz datatype. The whole
handling of DST is a bit bogus there, so I chose to make it use whatever
DST rules are in effect at the time of executig the query. not sure if
anybody is actuallyi *using* timetz though, it seems pretty
unpredictable just because of this...
Magnus Hagander
>> assuming this sideeffect is removed, though?
>
>I have no problem with the hashtable, only with preloading it with
>everything. What I'd like to see is that the table inherited at fork()
>contains just the data for the default timezone. (At least in the
>normal case where that setting hasn't been changed since postmaster
>start.)
Here's a patch doing this. Changes score_timezone not to use pg_tzset(),
and thus not loading all the zones in the cache. The actual timezone
being picked will be set using set_global_timezone() which in turn calls
pg_tzset() and loads it in the cache.
Magnus Hagander
spotted by Qingqing Zhou. The HASH_ENTER action now automatically
fails with elog(ERROR) on out-of-memory --- which incidentally lets
us eliminate duplicate error checks in quite a bunch of places. If
you really need the old return-NULL-on-out-of-memory behavior, you
can ask for HASH_ENTER_NULL. But there is now an Assert in that path
checking that you aren't hoping to get that behavior in a palloc-based
hash table.
Along the way, remove the old HASH_FIND_SAVE/HASH_REMOVE_SAVED actions,
which were not being used anywhere anymore, and were surely too ugly
and unsafe to want to see revived again.
* 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
use it, as per my proposal of yesterday. This gives us a means of
determining the zone offset to impute to an unlabeled timestamp that
is both efficient and reliable, unlike all our previous tries involving
mktime() and localtime(). The behavior for invalid or ambiguous times
at a DST transition is fixed to be really and truly "assume standard
time", fixing a bug that has come and gone repeatedly but was back
again in 7.4. (There is some ongoing discussion about whether we should
raise an error instead, but for the moment I'll make it do what it was
previously intended to do.)
Windows.
Recap: When running on a localized windows version, the timezone name
returned is also localized, and therefor does not match our lookup
table.
Solution: The registry contains both the name of the timezone in english
and the localized name. The patch adds code to scan the registry for the
localized name and gets the english name from that, and then rescans the
table.
I have tested this on a Swedish WinXP, and it works without problems.
The registry layout is the same in Win2k, but I haven't specifically
tested it. It's also the same on different languages but again only
Swedish is tested.
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.
machines, break tie scores by preferring shorter zone names over longer;
for names of equal length, prefer the alphabetically first name. This
yields for example 'EST5EDT' not 'America/New_York' for US eastern time.
On Windows, abandon the whole concept of inspecting the detailed behavior
of the system TZ library, because it doesn't bear inspection :-(. Instead
use a hardwired mapping table to select our zone name based on the
result of strftime %Z output. Windows code from Magnus Hagander.
timezone database for the system behavior we find ourselves in. Scan
backwards from current time and choose the zone that matches furthest
back. As per discussion a week or so back.
accurate matching of our time zone to the system's zone. This method is
able to distinguish Antarctica/Casey from Australia/Perth, as in Chris
K-L's recent example; and it is not materially slower than before, because
the extra checks generally don't get done against very many time zones.
It seems possible that with this test we'd be able to correctly identify
Windows timezones without looking at the timezone name, but I do not
have the ability to try it.
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.
database, not just ones that we cons up POSIX names for. This looks
grim but it seems to take less than a second even on a relatively slow
machine, and since it only happens once during postmaster startup, that
seems acceptable.
of correctly identifying the system's daylight-savings transition rules.
This still begs the question of how to look through the zic database to
find a matching zone definition, but at least now we'll have some chance
of recognizing the match when we find it.
Peter Eisentraut