Re: setting time zone during a transaction causes time warp

Thanks for the quick response! I haven't had a chance to test the patch
yet (this is being built by an automated system, so hand-patching is a bit
tough, but I'll adapt the patch to apply cleanly when I have some spare
time... or just upgrade to the latest version), but I just wanted you to
know that I really appreciate the fast and thorough responses.

...Robert

Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
02/20/2003 12:28 AM

To: Robert Haas/Tekconnect(at)Tekconnect
cc: pgsql-bugs(at)postgresql(dot)org
Fax to:
Subject: Re: [BUGS] setting time zone during a transaction
causes time warp

"Robert Haas" <Robert(dot)Haas(at)tekconnect(dot)com> writes:
> While using PostgreSQL 7.2.3, I discovered that if I set the time zone
> during the transaction, "now" takes on an incorrect value for the
> remainder of that transaction.

The problem seems to be restricted to the result of 'now'::timestamptz,
and not now() or 'now'::timestamp without time zone. I've applied the
attached patch to 7.3 --- it would probably work in 7.2 as well,
although I think you'd have to hand-patch because of the difference in
the nearby HAVE_INT64_TIMESTAMP #ifdefs.

regards, tom lane

*** src/backend/utils/adt/datetime.c~ Tue Jan 28 20:09:03 2003
--- src/backend/utils/adt/datetime.c Thu Feb 20 00:19:50 2003
***************
*** 1242,1250 ****
case DTK_NOW:
tmask = (DTK_DATE_M |
DTK_TIME_M | DTK_M(TZ));
*dtype = DTK_DATE;
! GetCurrentTimeUsec(tm,
fsec);
! if (tzp != NULL)
! *tzp =
CTimeZone;
break;

case DTK_YESTERDAY:
--- 1242,1248 ----
case DTK_NOW:
tmask = (DTK_DATE_M |
DTK_TIME_M | DTK_M(TZ));
*dtype = DTK_DATE;
! GetCurrentTimeUsec(tm,
fsec, tzp);
break;

case DTK_YESTERDAY:
***************
*** 1958,1964 ****
case DTK_NOW:
tmask = DTK_TIME_M;
*dtype = DTK_TIME;
! GetCurrentTimeUsec(tm,
fsec);
break;

case DTK_ZULU:
--- 1956,1962 ----
case DTK_NOW:
tmask = DTK_TIME_M;
*dtype = DTK_TIME;
! GetCurrentTimeUsec(tm,
fsec, NULL);
break;

case DTK_ZULU:
*** src/backend/utils/adt/nabstime.c~ Thu Dec 12 14:17:04 2002
--- src/backend/utils/adt/nabstime.c Thu Feb 20 00:19:50 2003
***************
*** 243,267 ****
int tz;

abstime2tm(GetCurrentTransactionStartTime(), &tz, tm,
NULL);
-
- return;
} /* GetCurrentDateTime() */


void
! GetCurrentTimeUsec(struct tm * tm, fsec_t *fsec)
{
int tz;
int usec;

abstime2tm(GetCurrentTransactionStartTimeUsec(&usec),
&tz, tm, NULL);
#ifdef HAVE_INT64_TIMESTAMP
*fsec = usec;
#else
*fsec = usec * 1.0e-6;
#endif
-
- return;
} /* GetCurrentTimeUsec() */


--- 243,266 ----
int tz;

abstime2tm(GetCurrentTransactionStartTime(), &tz, tm,
NULL);
} /* GetCurrentDateTime() */


void
! GetCurrentTimeUsec(struct tm * tm, fsec_t *fsec, int *tzp)
{
int tz;
int usec;

abstime2tm(GetCurrentTransactionStartTimeUsec(&usec),
&tz, tm, NULL);
+ /* Note: don't pass NULL tzp directly to abstime2tm */
+ if (tzp != NULL)
+ *tzp = tz;
#ifdef HAVE_INT64_TIMESTAMP
*fsec = usec;
#else
*fsec = usec * 1.0e-6;
#endif
} /* GetCurrentTimeUsec() */


*** src/include/utils/datetime.h~ Wed Jan 15 19:27:17 2003
--- src/include/utils/datetime.h Thu Feb 20 00:19:51 2003
***************
*** 261,267 ****


extern void GetCurrentDateTime(struct tm * tm);
! extern void GetCurrentTimeUsec(struct tm * tm, fsec_t *fsec);
extern void j2date(int jd, int *year, int *month, int *day);
extern int date2j(int year, int month, int day);

--- 261,267 ----


extern void GetCurrentDateTime(struct tm * tm);
! extern void GetCurrentTimeUsec(struct tm * tm, fsec_t *fsec, int *tzp);
extern void j2date(int jd, int *year, int *month, int *day);
extern int date2j(int year, int month, int day);