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timestamptz_trunc() should only recalculate the timezone when truncating 

to DAY precision or coarser; leave the timezone alone when precision is
HOUR or less.  This avoids surprises for inputs near a DST transition
time, as per example from Matthew Gabeler-Lee.  (The only reason we
recalculate at all is so that outputs that are supposed to represent
days will come out as local midnight, and that's not relevant for sub-day
precision.)
This commit is contained in:
Tom Lane 2004-11-01 22:00:30 +00:00
parent 5ba04cd9f1
commit c4acbb843b
1 changed files with 15 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
src/backend/utils/adt/timestamp.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.113 2004/08/30 02:54:39 momjian Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.114 2004/11/01 22:00:30 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -2842,6 +2842,7 @@ timestamptz_trunc(PG_FUNCTION_ARGS)
int tz;
int type,
val;
bool redotz = false;
char *lowunits;
fsec_t fsec;
char *tzn;
@ -2872,6 +2873,7 @@ timestamptz_trunc(PG_FUNCTION_ARGS)
tm->tm_min = 0;
tm->tm_sec = 0;
fsec = 0;
redotz = true;
break;
/* one may consider DTK_THOUSAND and DTK_HUNDRED... */
case DTK_MILLENNIUM:
@ -2885,12 +2887,14 @@ timestamptz_trunc(PG_FUNCTION_ARGS)
tm->tm_year = ((tm->tm_year + 999) / 1000) * 1000 - 999;
else
tm->tm_year = -((999 - (tm->tm_year - 1)) / 1000) * 1000 + 1;
/* FALL THRU */
case DTK_CENTURY:
/* truncating to the century? as above: -100, 1, 101... */
if (tm->tm_year > 0)
tm->tm_year = ((tm->tm_year + 99) / 100) * 100 - 99;
else
tm->tm_year = -((99 - (tm->tm_year - 1)) / 100) * 100 + 1;
/* FALL THRU */
case DTK_DECADE:
/*
@ -2904,18 +2908,26 @@ timestamptz_trunc(PG_FUNCTION_ARGS)
else
tm->tm_year = -((8 - (tm->tm_year - 1)) / 10) * 10;
}
/* FALL THRU */
case DTK_YEAR:
tm->tm_mon = 1;
/* FALL THRU */
case DTK_QUARTER:
tm->tm_mon = (3 * ((tm->tm_mon - 1) / 3)) + 1;
/* FALL THRU */
case DTK_MONTH:
tm->tm_mday = 1;
/* FALL THRU */
case DTK_DAY:
tm->tm_hour = 0;
redotz = true; /* for all cases >= DAY */
/* FALL THRU */
case DTK_HOUR:
tm->tm_min = 0;
/* FALL THRU */
case DTK_MINUTE:
tm->tm_sec = 0;
/* FALL THRU */
case DTK_SECOND:
fsec = 0;
break;
@ -2941,7 +2953,8 @@ timestamptz_trunc(PG_FUNCTION_ARGS)
result = 0;
}
tz = DetermineLocalTimeZone(tm);
if (redotz)
tz = DetermineLocalTimeZone(tm);
if (tm2timestamp(tm, fsec, &tz, &result) != 0)
ereport(ERROR,