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timestamp.h
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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) 1996-2012, 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 #include <math.h> #include <limits.h> #include <float.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 * * We have two implementations, one that uses int64 values with units of * microseconds, and one that uses double values with units of seconds. * * TimeOffset and fsec_t are convenience typedefs for temporary variables * that are of different types in the two cases. Do not use fsec_t in values * stored on-disk, since it is not the same size in both implementations. * Also, fsec_t is only meant for *fractional* seconds; beware of overflow * if the value you need to store could be many seconds. */ #ifdef HAVE_INT64_TIMESTAMP typedef int64 Timestamp; typedef int64 TimestampTz; typedef int64 TimeOffset; typedef int32 fsec_t; /* fractional seconds (in microseconds) */ #else typedef double Timestamp; typedef double TimestampTz; typedef double TimeOffset; typedef double fsec_t; /* fractional seconds (in seconds) */ #endif 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; #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) /* * DT_NOBEGIN represents timestamp -infinity; DT_NOEND represents +infinity */ #ifdef HAVE_INT64_TIMESTAMP #define DT_NOBEGIN (-INT64CONST(0x7fffffffffffffff) - 1) #define DT_NOEND (INT64CONST(0x7fffffffffffffff)) #else /* !HAVE_INT64_TIMESTAMP */ #ifdef HUGE_VAL #define DT_NOBEGIN (-HUGE_VAL) #define DT_NOEND (HUGE_VAL) #else #define DT_NOBEGIN (-DBL_MAX) #define DT_NOEND (DBL_MAX) #endif #endif /* HAVE_INT64_TIMESTAMP */ #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. * * IS_VALID_JULIAN checks the minimum date exactly, but is a bit sloppy * about the maximum, since it's far enough out to not be especially * interesting. */ #define JULIAN_MINYEAR (-4713) #define JULIAN_MINMONTH (11) #define JULIAN_MINDAY (24) #define JULIAN_MAXYEAR (5874898) #define IS_VALID_JULIAN(y,m,d) \ (((y) > JULIAN_MINYEAR \ || ((y) == JULIAN_MINYEAR && \ ((m) > JULIAN_MINMONTH \ || ((m) == JULIAN_MINMONTH && (d) >= JULIAN_MINDAY)))) \ && (y) < JULIAN_MAXYEAR) #define JULIAN_MAX (2147483494) /* == date2j(JULIAN_MAXYEAR, 1, 1) */ /* 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) */ #endif /* DATATYPE_TIMESTAMP_H */