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Make extract() do something more reasonable with infinite datetimes.

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Historically, extract() just returned zero for any case involving an
infinite timestamp[tz] input; even cases in which the unit name was
invalid.  This is not very sensible.  Instead, return infinity or
-infinity as appropriate when the requested field is one that is
monotonically increasing (e.g, year, epoch), or NULL when it is not
(e.g., day, hour).  Also, throw the expected errors for bad unit names.

BACKWARDS INCOMPATIBLE CHANGE

Vitaly Burovoy, reviewed by Vik Fearing
This commit is contained in:
Tom Lane
2016-01-21 22:26:20 -05:00
parent d9b9289c83
commit 647d87c56a
4 changed files with 405 additions and 12 deletions
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111
src/backend/utils/adt/timestamp.c
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@ -4311,6 +4311,83 @@ date2isoyearday(int year, int mon, int mday)
return date2j(year, mon, mday) - isoweek2j(date2isoyear(year, mon, mday), 1) + 1;
}
/*
* NonFiniteTimestampTzPart
*
* Used by timestamp_part and timestamptz_part when extracting from infinite
* timestamp[tz]. Returns +/-Infinity if that is the appropriate result,
* otherwise returns zero (which should be taken as meaning to return NULL).
*
* Errors thrown here for invalid units should exactly match those that
* would be thrown in the calling functions, else there will be unexpected
* discrepancies between finite- and infinite-input cases.
*/
static float8
NonFiniteTimestampTzPart(int type, int unit, char *lowunits,
bool isNegative, bool isTz)
{
if ((type != UNITS) && (type != RESERV))
{
if (isTz)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("timestamp with time zone units \"%s\" not recognized",
lowunits)));
else
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("timestamp units \"%s\" not recognized",
lowunits)));
}
switch (unit)
{
/* Oscillating units */
case DTK_MICROSEC:
case DTK_MILLISEC:
case DTK_SECOND:
case DTK_MINUTE:
case DTK_HOUR:
case DTK_DAY:
case DTK_MONTH:
case DTK_QUARTER:
case DTK_WEEK:
case DTK_DOW:
case DTK_ISODOW:
case DTK_DOY:
case DTK_TZ:
case DTK_TZ_MINUTE:
case DTK_TZ_HOUR:
return 0.0;
/* Monotonically-increasing units */
case DTK_YEAR:
case DTK_DECADE:
case DTK_CENTURY:
case DTK_MILLENNIUM:
case DTK_JULIAN:
case DTK_ISOYEAR:
case DTK_EPOCH:
if (isNegative)
return -get_float8_infinity();
else
return get_float8_infinity();
default:
if (isTz)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("timestamp with time zone units \"%s\" not supported",
lowunits)));
else
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("timestamp units \"%s\" not supported",
lowunits)));
return 0.0; /* keep compiler quiet */
}
}
/* timestamp_part()
* Extract specified field from timestamp.
*/
@ -4327,12 +4404,6 @@ timestamp_part(PG_FUNCTION_ARGS)
struct pg_tm tt,
*tm = &tt;
if (TIMESTAMP_NOT_FINITE(timestamp))
{
result = 0;
PG_RETURN_FLOAT8(result);
}
lowunits = downcase_truncate_identifier(VARDATA_ANY(units),
VARSIZE_ANY_EXHDR(units),
false);
@ -4341,6 +4412,17 @@ timestamp_part(PG_FUNCTION_ARGS)
if (type == UNKNOWN_FIELD)
type = DecodeSpecial(0, lowunits, &val);
if (TIMESTAMP_NOT_FINITE(timestamp))
{
result = NonFiniteTimestampTzPart(type, val, lowunits,
TIMESTAMP_IS_NOBEGIN(timestamp),
false);
if (result)
PG_RETURN_FLOAT8(result);
else
PG_RETURN_NULL();
}
if (type == UNITS)
{
if (timestamp2tm(timestamp, NULL, tm, &fsec, NULL, NULL) != 0)
@ -4538,12 +4620,6 @@ timestamptz_part(PG_FUNCTION_ARGS)
struct pg_tm tt,
*tm = &tt;
if (TIMESTAMP_NOT_FINITE(timestamp))
{
result = 0;
PG_RETURN_FLOAT8(result);
}
lowunits = downcase_truncate_identifier(VARDATA_ANY(units),
VARSIZE_ANY_EXHDR(units),
false);
@ -4552,6 +4628,17 @@ timestamptz_part(PG_FUNCTION_ARGS)
if (type == UNKNOWN_FIELD)
type = DecodeSpecial(0, lowunits, &val);
if (TIMESTAMP_NOT_FINITE(timestamp))
{
result = NonFiniteTimestampTzPart(type, val, lowunits,
TIMESTAMP_IS_NOBEGIN(timestamp),
true);
if (result)
PG_RETURN_FLOAT8(result);
else
PG_RETURN_NULL();
}
if (type == UNITS)
{
if (timestamp2tm(timestamp, &tz, tm, &fsec, NULL, NULL) != 0)