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Attached patch gets rid of the global timezone in the following steps:

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* 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
This commit is contained in:
Bruce Momjian
2005-04-19 03:13:59 +00:00
parent dd39dd232f
commit aa8bdab272
11 changed files with 234 additions and 192 deletions
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110
src/backend/commands/variable.c
View File

@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/variable.c,v 1.105 2004/12/31 21:59:42 pgsql Exp $
* $PostgreSQL: pgsql/src/backend/commands/variable.c,v 1.106 2005/04/19 03:13:58 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -315,13 +315,13 @@ assign_timezone(const char *value, bool doit, GucSource source)
* UNKNOWN as the canonical spelling.
*
* During GUC initialization, since the timezone library isn't
* set up yet, pg_get_current_timezone will return NULL and we
* set up yet, pg_get_timezone_name will return NULL and we
* will leave the setting as UNKNOWN. If this isn't
* overridden from the config file then
* pg_timezone_initialize() will eventually select a default
* value from the environment.
*/
const char *curzone = pg_get_current_timezone();
const char *curzone = pg_get_timezone_name(global_timezone);
if (curzone)
value = curzone;
@ -329,90 +329,36 @@ assign_timezone(const char *value, bool doit, GucSource source)
else
{
/*
* Otherwise assume it is a timezone name.
*
* We have to actually apply the change before we can have any
* hope of checking it. So, save the old value in case we
* have to back out. We have to copy since
* pg_get_current_timezone returns a pointer to its static
* state.
*
* This would all get a lot simpler if the TZ library had a
* better API that would let us look up and test a timezone
* name without making it the default.
* Otherwise assume it is a timezone name, and try to load it.
*/
const char *cur_tz;
char *save_tz;
bool known,
acceptable;
pg_tz *new_tz;
cur_tz = pg_get_current_timezone();
if (cur_tz)
save_tz = pstrdup(cur_tz);
else
save_tz = NULL;
new_tz = pg_tzset(value);
known = pg_tzset(value);
acceptable = known ? tz_acceptable() : false;
if (doit && known && acceptable)
if (!new_tz)
{
/* Keep the changed TZ */
HasCTZSet = false;
ereport((source >= PGC_S_INTERACTIVE) ? ERROR : LOG,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("unrecognized time zone name: \"%s\"",
value)));
return NULL;
}
else
if (!tz_acceptable(new_tz))
{
/*
* Revert to prior TZ setting; note we haven't changed
* HasCTZSet in this path, so if we were previously using
* a fixed offset, we still are.
*/
if (save_tz)
pg_tzset(save_tz);
else
{
/*
* TZ library wasn't initialized yet. Annoyingly, we
* will come here during startup because guc-file.l
* checks the value with doit = false before actually
* applying. The best approach seems to be as follows:
*
* 1. known && acceptable: leave the setting in place,
* since we'll apply it soon anyway. This is mainly
* so that any log messages printed during this
* interval are timestamped with the user's requested
* timezone.
*
* 2. known && !acceptable: revert to GMT for lack of any
* better idea. (select_default_timezone() may get
* called later to undo this.)
*
* 3. !known: no need to do anything since TZ library did
* not change its state.
*
* Again, this should all go away sometime soon.
*/
if (known && !acceptable)
pg_tzset("GMT");
}
/* Complain if it was bad */
if (!known)
{
ereport((source >= PGC_S_INTERACTIVE) ? ERROR : LOG,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("unrecognized time zone name: \"%s\"",
value)));
return NULL;
}
if (!acceptable)
{
ereport((source >= PGC_S_INTERACTIVE) ? ERROR : LOG,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("time zone \"%s\" appears to use leap seconds",
value),
errdetail("PostgreSQL does not support leap seconds.")));
return NULL;
}
ereport((source >= PGC_S_INTERACTIVE) ? ERROR : LOG,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("time zone \"%s\" appears to use leap seconds",
value),
errdetail("PostgreSQL does not support leap seconds.")));
return NULL;
}
if (doit)
{
/* Save the changed TZ */
global_timezone = new_tz;
HasCTZSet = false;
}
}
}
@ -459,7 +405,7 @@ show_timezone(void)
IntervalPGetDatum(&interval)));
}
else
tzn = pg_get_current_timezone();
tzn = pg_get_timezone_name(global_timezone);
if (tzn != NULL)
return tzn;