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/*-------------------------------------------------------------------------
*
* timestamp.h
* Timestamp and Interval typedefs and related macros.
*
* Note: this file must be includable in both frontend and backend contexts.
*
* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/datatype/timestamp.h
*
*-------------------------------------------------------------------------
*/
#ifndef DATATYPE_TIMESTAMP_H
#define DATATYPE_TIMESTAMP_H
/*
* Timestamp represents absolute time.
*
* Interval represents delta time. Keep track of months (and years), days,
* and hours/minutes/seconds separately since the elapsed time spanned is
* unknown until instantiated relative to an absolute time.
*
* Note that Postgres uses "time interval" to mean a bounded interval,
* consisting of a beginning and ending time, not a time span - thomas 97/03/20
*
* Timestamps, as well as the h/m/s fields of intervals, are stored as
* int64 values with units of microseconds. (Once upon a time they were
* double values with units of seconds.)
*
* TimeOffset and fsec_t are convenience typedefs for temporary variables.
* Do not use fsec_t in values stored on-disk.
* Also, fsec_t is only meant for *fractional* seconds; beware of overflow
* if the value you need to store could be many seconds.
*/
typedef int64 Timestamp;
typedef int64 TimestampTz;
typedef int64 TimeOffset;
typedef int32 fsec_t; /* fractional seconds (in microseconds) */
/*
* Storage format for type interval.
*/
typedef struct
{
TimeOffset time; /* all time units other than days, months and
* years */
int32 day; /* days, after time for alignment */
int32 month; /* months and years, after time for alignment */
} Interval;
/*
* Data structure representing a broken-down interval.
*
* For historical reasons, this is modeled on struct pg_tm for timestamps.
* Unlike the situation for timestamps, there's no magic interpretation
* needed for months or years: they're just zero or not. Note that fields
* can be negative; however, because of the divisions done while converting
* from struct Interval, only tm_mday could be INT_MIN. This is important
* because we may need to negate the values in some code paths.
*/
struct pg_itm
{
int tm_usec;
int tm_sec;
int tm_min;
int64 tm_hour; /* needs to be wide */
int tm_mday;
int tm_mon;
int tm_year;
};
/*
* Data structure for decoding intervals. We could just use struct pg_itm,
* but then the requirement for tm_usec to be 64 bits would propagate to
* places where it's not really needed. Also, omitting the fields that
* aren't used during decoding seems like a good error-prevention measure.
*/
struct pg_itm_in
{
int64 tm_usec; /* needs to be wide */
int tm_mday;
int tm_mon;
int tm_year;
};
/* Limits on the "precision" option (typmod) for these data types */
#define MAX_TIMESTAMP_PRECISION 6
#define MAX_INTERVAL_PRECISION 6
/*
* Round off to MAX_TIMESTAMP_PRECISION decimal places.
* Note: this is also used for rounding off intervals.
*/
#define TS_PREC_INV 1000000.0
#define TSROUND(j) (rint(((double) (j)) * TS_PREC_INV) / TS_PREC_INV)
/*
* Assorted constants for datetime-related calculations
*/
#define DAYS_PER_YEAR 365.25 /* assumes leap year every four years */
#define MONTHS_PER_YEAR 12
/*
* DAYS_PER_MONTH is very imprecise. The more accurate value is
* 365.2425/12 = 30.436875, or '30 days 10:29:06'. Right now we only
* return an integral number of days, but someday perhaps we should
* also return a 'time' value to be used as well. ISO 8601 suggests
* 30 days.
*/
#define DAYS_PER_MONTH 30 /* assumes exactly 30 days per month */
#define HOURS_PER_DAY 24 /* assume no daylight savings time changes */
/*
* This doesn't adjust for uneven daylight savings time intervals or leap
* seconds, and it crudely estimates leap years. A more accurate value
* for days per years is 365.2422.
*/
#define SECS_PER_YEAR (36525 * 864) /* avoid floating-point computation */
#define SECS_PER_DAY 86400
#define SECS_PER_HOUR 3600
#define SECS_PER_MINUTE 60
#define MINS_PER_HOUR 60
#define USECS_PER_DAY INT64CONST(86400000000)
#define USECS_PER_HOUR INT64CONST(3600000000)
#define USECS_PER_MINUTE INT64CONST(60000000)
#define USECS_PER_SEC INT64CONST(1000000)
/*
* We allow numeric timezone offsets up to 15:59:59 either way from Greenwich.
* Currently, the record holders for wackiest offsets in actual use are zones
* Asia/Manila, at -15:56:00 until 1844, and America/Metlakatla, at +15:13:42
* until 1867. If we were to reject such values we would fail to dump and
* restore old timestamptz values with these zone settings.
*/
#define MAX_TZDISP_HOUR 15 /* maximum allowed hour part */
#define TZDISP_LIMIT ((MAX_TZDISP_HOUR + 1) * SECS_PER_HOUR)
/*
* We reserve the minimum and maximum integer values to represent
* timestamp (or timestamptz) -infinity and +infinity.
*/
#define TIMESTAMP_MINUS_INFINITY PG_INT64_MIN
#define TIMESTAMP_INFINITY PG_INT64_MAX
/*
* Historically these alias for infinity have been used.
*/
#define DT_NOBEGIN TIMESTAMP_MINUS_INFINITY
#define DT_NOEND TIMESTAMP_INFINITY
#define TIMESTAMP_NOBEGIN(j) \
do {(j) = DT_NOBEGIN;} while (0)
#define TIMESTAMP_IS_NOBEGIN(j) ((j) == DT_NOBEGIN)
#define TIMESTAMP_NOEND(j) \
do {(j) = DT_NOEND;} while (0)
#define TIMESTAMP_IS_NOEND(j) ((j) == DT_NOEND)
#define TIMESTAMP_NOT_FINITE(j) (TIMESTAMP_IS_NOBEGIN(j) || TIMESTAMP_IS_NOEND(j))
/*
* Julian date support.
*
* date2j() and j2date() nominally handle the Julian date range 0..INT_MAX,
* or 4714-11-24 BC to 5874898-06-03 AD. In practice, date2j() will work and
* give correct negative Julian dates for dates before 4714-11-24 BC as well.
* We rely on it to do so back to 4714-11-01 BC. Allowing at least one day's
* slop is necessary so that timestamp rotation doesn't produce dates that
* would be rejected on input. For example, '4714-11-24 00:00 GMT BC' is a
* legal timestamptz value, but in zones east of Greenwich it would print as
* sometime in the afternoon of 4714-11-23 BC; if we couldn't process such a
* date we'd have a dump/reload failure. So the idea is for IS_VALID_JULIAN
* to accept a slightly wider range of dates than we really support, and
* then we apply the exact checks in IS_VALID_DATE or IS_VALID_TIMESTAMP,
* after timezone rotation if any. To save a few cycles, we can make
* IS_VALID_JULIAN check only to the month boundary, since its exact cutoffs
* are not very critical in this scheme.
*
* It is correct that JULIAN_MINYEAR is -4713, not -4714; it is defined to
* allow easy comparison to tm_year values, in which we follow the convention
* that tm_year <= 0 represents abs(tm_year)+1 BC.
*/
#define JULIAN_MINYEAR (-4713)
#define JULIAN_MINMONTH (11)
#define JULIAN_MINDAY (24)
#define JULIAN_MAXYEAR (5874898)
#define JULIAN_MAXMONTH (6)
#define JULIAN_MAXDAY (3)
#define IS_VALID_JULIAN(y,m,d) \
(((y) > JULIAN_MINYEAR || \
((y) == JULIAN_MINYEAR && ((m) >= JULIAN_MINMONTH))) && \
((y) < JULIAN_MAXYEAR || \
((y) == JULIAN_MAXYEAR && ((m) < JULIAN_MAXMONTH))))
/* Julian-date equivalents of Day 0 in Unix and Postgres reckoning */
#define UNIX_EPOCH_JDATE 2440588 /* == date2j(1970, 1, 1) */
#define POSTGRES_EPOCH_JDATE 2451545 /* == date2j(2000, 1, 1) */
/*
* Range limits for dates and timestamps.
*
* We have traditionally allowed Julian day zero as a valid datetime value,
* so that is the lower bound for both dates and timestamps.
*
* The upper limit for dates is 5874897-12-31, which is a bit less than what
* the Julian-date code can allow. For timestamps, the upper limit is
* 294276-12-31. The int64 overflow limit would be a few days later; again,
* leaving some slop avoids worries about corner-case overflow, and provides
* a simpler user-visible definition.
*/
/* First allowed date, and first disallowed date, in Julian-date form */
#define DATETIME_MIN_JULIAN (0)
#define DATE_END_JULIAN (2147483494) /* == date2j(JULIAN_MAXYEAR, 1, 1) */
#define TIMESTAMP_END_JULIAN (109203528) /* == date2j(294277, 1, 1) */
/* Timestamp limits */
#define MIN_TIMESTAMP INT64CONST(-211813488000000000)
/* == (DATETIME_MIN_JULIAN - POSTGRES_EPOCH_JDATE) * USECS_PER_DAY */
#define END_TIMESTAMP INT64CONST(9223371331200000000)
/* == (TIMESTAMP_END_JULIAN - POSTGRES_EPOCH_JDATE) * USECS_PER_DAY */
/* Range-check a date (given in Postgres, not Julian, numbering) */
#define IS_VALID_DATE(d) \
((DATETIME_MIN_JULIAN - POSTGRES_EPOCH_JDATE) <= (d) && \
(d) < (DATE_END_JULIAN - POSTGRES_EPOCH_JDATE))
/* Range-check a timestamp */
#define IS_VALID_TIMESTAMP(t) (MIN_TIMESTAMP <= (t) && (t) < END_TIMESTAMP)
#endif /* DATATYPE_TIMESTAMP_H */
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