mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-09-30 16:01:15 +02:00
I think I've finally identified the cause of the off-by-one-second
issue in timestamp conversion that we hacked around for so long by ignoring the seconds field from localtime(). It's simple: you have to watch out for platform-specific roundoff error when reducing a possibly-fractional timestamp to integral time_t form. In particular we should subtract off the already-determined fractional fsec field. This should be enough to get an exact answer with int64 timestamps; with float timestamps, throw in a rint() call just to be sure.
This commit is contained in:
parent
d534b9ee9e
commit
87de80e95a
@ -8,7 +8,7 @@
|
||||
*
|
||||
*
|
||||
* IDENTIFICATION
|
||||
* $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.106 2004/05/21 05:08:02 tgl Exp $
|
||||
* $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.107 2004/05/31 18:31:51 tgl Exp $
|
||||
*
|
||||
*-------------------------------------------------------------------------
|
||||
*/
|
||||
@ -933,22 +933,18 @@ dt2time(Timestamp jd, int *hour, int *min, int *sec, fsec_t *fsec)
|
||||
* local time zone. If out of this range, leave as GMT. - tgl 97/05/27
|
||||
*/
|
||||
int
|
||||
timestamp2tm(Timestamp dt, int *tzp, struct pg_tm * tm, fsec_t *fsec, char **tzn)
|
||||
timestamp2tm(Timestamp dt, int *tzp, struct pg_tm *tm, fsec_t *fsec, char **tzn)
|
||||
{
|
||||
#ifdef HAVE_INT64_TIMESTAMP
|
||||
int date,
|
||||
date0;
|
||||
int date;
|
||||
int64 time;
|
||||
#else
|
||||
double date,
|
||||
date0;
|
||||
double date;
|
||||
double time;
|
||||
#endif
|
||||
time_t utime;
|
||||
struct pg_tm *tx;
|
||||
|
||||
date0 = POSTGRES_EPOCH_JDATE;
|
||||
|
||||
/*
|
||||
* If HasCTZSet is true then we have a brute force time zone
|
||||
* specified. Go ahead and rotate to the local time zone since we will
|
||||
@ -983,11 +979,11 @@ timestamp2tm(Timestamp dt, int *tzp, struct pg_tm * tm, fsec_t *fsec, char **tzn
|
||||
#endif
|
||||
|
||||
/* Julian day routine does not work for negative Julian days */
|
||||
if (date < -date0)
|
||||
if (date < -POSTGRES_EPOCH_JDATE)
|
||||
return -1;
|
||||
|
||||
/* add offset to go from J2000 back to standard Julian date */
|
||||
date += date0;
|
||||
date += POSTGRES_EPOCH_JDATE;
|
||||
|
||||
j2date((int) date, &tm->tm_year, &tm->tm_mon, &tm->tm_mday);
|
||||
dt2time(time, &tm->tm_hour, &tm->tm_min, &tm->tm_sec, fsec);
|
||||
@ -1014,11 +1010,19 @@ timestamp2tm(Timestamp dt, int *tzp, struct pg_tm * tm, fsec_t *fsec, char **tzn
|
||||
*/
|
||||
else if (IS_VALID_UTIME(tm->tm_year, tm->tm_mon, tm->tm_mday))
|
||||
{
|
||||
/*
|
||||
* Convert to integer, avoiding platform-specific
|
||||
* roundoff-in-wrong-direction errors, and adjust to
|
||||
* Unix epoch. Note we have to do this in one step
|
||||
* because the intermediate result before adjustment
|
||||
* won't necessarily fit in an int32.
|
||||
*/
|
||||
#ifdef HAVE_INT64_TIMESTAMP
|
||||
utime = ((dt / INT64CONST(1000000))
|
||||
+ ((date0 - UNIX_EPOCH_JDATE) * INT64CONST(86400)));
|
||||
utime = (dt - *fsec) / INT64CONST(1000000) +
|
||||
(POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * 86400;
|
||||
#else
|
||||
utime = (dt + ((date0 - UNIX_EPOCH_JDATE) * 86400));
|
||||
utime = rint(dt - *fsec +
|
||||
(POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * 86400);
|
||||
#endif
|
||||
|
||||
tx = pg_localtime(&utime);
|
||||
|
Loading…
Reference in New Issue
Block a user