diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml index 62117820f74..daabb71fb62 100644 --- a/doc/src/sgml/datatype.sgml +++ b/doc/src/sgml/datatype.sgml @@ -1,5 +1,5 @@ @@ -1346,29 +1346,35 @@ SELECT b, char_length(b) FROM test2; Time zones, and time-zone conventions, are influenced by - political decisions, not just geometry. Time zones around the + political decisions, not just earth geometry. Time zones around the world became somewhat standardized during the 1900's, but continue to be prone to arbitrary changes. PostgreSQL uses your operating - system's underlying features to provide time-zone + system's underlying features to provide output time-zone support, and these systems usually contain information for only the time period 1902 through 2038 (corresponding to the full range of conventional Unix system time). - timestamp with time zone will use time zone - information only within that year range, and assumes that times - are in UTC outside that range. + timestamp with time zone and time with time + zone will use time zone + information only within that year range, and assume that times + outside that range are in UTC. - To ensure compatibility to earlier versions of - PostgreSQL - we continue to provide datetime + To ensure an upgrade path from versions of + PostgreSQL earlier than 7.0, + we recognize datetime (equivalent to timestamp) and - timespan (equivalent to interval), - however support for these is now restricted to having an + timespan (equivalent to interval). + These types are + now restricted to having an implicit translation to timestamp and - interval, and these name mappings will be removed in - the next version. + interval, and + support for these will be removed in the next release of + PostgreSQL (likely named 7.3). + + + The types abstime and reltime are lower precision types which are used internally. You are discouraged from using any of these types in new @@ -1402,7 +1408,8 @@ SELECT b, char_length(b) FROM test2; SQL standard requires. See for the exact parsing rules of date/time input and for the - recognized time zones. + recognized text fields including months, days of the week, and + time zones. @@ -1431,7 +1438,7 @@ SELECT b, char_length(b) FROM test2; - The following are possible inputs for the date type. + The following are some possible inputs for the date type. Date Input @@ -1479,6 +1486,10 @@ SELECT b, char_length(b) FROM test2; 99008Year and day of year + + J2451187 + Julian day + January 8, 99 BC Year 99 before the Common Era @@ -1487,116 +1498,6 @@ SELECT b, char_length(b) FROM test2;
- - - - Month Abbreviations - - - - Month - Abbreviations - - - - - April - Apr - - - August - Aug - - - December - Dec - - - February - Feb - - - January - Jan - - - July - Jul - - - June - Jun - - - March - Mar - - - November - Nov - - - October - Oct - - - September - Sep, Sept - - - -
- - - - The month May has no explicit abbreviation, for obvious reasons. - - - - - - - Day of the Week Abbreviations - - - - Day - Abbreviation - - - - - Sunday - Sun - - - Monday - Mon - - - Tuesday - Tue, Tues - - - Wednesday - Wed, Weds - - - Thursday - Thu, Thur, Thurs - - - Friday - Fri - - - Saturday - Sat - - - -
- @@ -1655,14 +1556,6 @@ SELECT b, char_length(b) FROM test2; 04:05 PM Same as 16:05; input hour must be <= 12 - - z - Same as 00:00:00 - - - zulu - Same as 00:00:00 - allballs Same as 00:00:00 diff --git a/doc/src/sgml/datetime.sgml b/doc/src/sgml/datetime.sgml index cc1f121622f..32ddd2365b4 100644 --- a/doc/src/sgml/datetime.sgml +++ b/doc/src/sgml/datetime.sgml @@ -1,11 +1,197 @@ Date/Time Support + + PostgreSQL uses an internal heuristic + parser for all date/time support. Dates and times are input as + strings, and are broken up into distinct fields with a preliminary + determination of what kind of information may be in the + field. Each field is interpreted and either assigned a numeric + value, ignored, or rejected. + The parser contains internal lookup tables for all textual fields, + including months, days of the week, and time + zones. + + + + This appendix includes information on the content of these + lookup tables and describes the steps used by the parser to decode + dates and times. + + + + Date/Time Keywords + + + + Month Abbreviations + + + + Month + Abbreviations + + + + + April + Apr + + + August + Aug + + + December + Dec + + + February + Feb + + + January + Jan + + + July + Jul + + + June + Jun + + + March + Mar + + + November + Nov + + + October + Oct + + + September + Sep, Sept + + + +
+ + + + The month May has no explicit abbreviation, for obvious reasons. + + + + + + + Day of the Week Abbreviations + + + + Day + Abbreviation + + + + + Sunday + Sun + + + Monday + Mon + + + Tuesday + Tue, Tues + + + Wednesday + Wed, Weds + + + Thursday + Thu, Thur, Thurs + + + Friday + Fri + + + Saturday + Sat + + + +
+ + + + + <productname>PostgreSQL</productname> Field Modifiers + Field Modifiers + + + + Identifier + Description + + + + + ABSTIME + Keyword ignored + + + AM + Time is before 12:00 + + + AT + Keyword ignored + + + JULIAN, JD, J + Next field is Julian Day + + + ON + Keyword ignored + + + PM + Time is on or after after 12:00 + + + T + Next field is time + + + +
+ + + + The keyword ABSTIME is ignored for historical + reasons; in very old releases of + PostgreSQL invalid ABSTIME + fields were emitted as Invalid Abstime. This is no + longer the case however and this keyword will likely be dropped in + a future release. + + + Time Zones @@ -19,6 +205,15 @@ Date/time details system interface to provide access to general, cross-timezone information. The underlying OS is used to provide time zone information for output, however. + + + + The following table of time zones recognized by + PostgreSQL is organized by time + zone offset from UTC, rather than alphabetically; this is intended + to faciliate + matching local usage with recognized abreviations for cases where + these might differ. <productname>PostgreSQL</productname> Recognized Time Zones @@ -360,6 +555,26 @@ Date/time details +00:00Greenwich Mean Time + + UT + +00:00 + Universal Time + + + UTC + +00:00 + Universal Time, Coordinated + + + Z + +00:00 + Same as UTC + + + ZULU + +00:00 + Same as UTC + WET +00:00 @@ -603,13 +818,15 @@ Date/time details - If the token contains a colon (":"), this is a time string. + If the numeric token contains a colon (":"), this is a time + string. Include all subsequent digits and colons. - If the token contains a dash ("-"), slash ("/"), or dot ("."), + If the numeric token contains a dash ("-"), slash ("/"), or + two or more dots ("."), this is a date string which may have a text month. @@ -617,7 +834,8 @@ Date/time details If the token is numeric only, then it is either a single field - or an ISO-8601 concatenated date (e.g. 19990113 for January 13, 1999) + or an ISO-8601 concatenated date + (e.g. 19990113 for January 13, 1999) or time (e.g. 141516 for 14:15:16). @@ -689,6 +907,13 @@ Date/time details + + + If four or six digits and a year has already been read, then + interpret as a time. + + + If four or more digits, then interpret as a year. @@ -732,10 +957,10 @@ Date/time details - If BC has been specified, negate the year and offset by one for + If BC has been specified, negate the year and add one for internal storage (there is no year zero in the Gregorian calendar, so numerically - 1BC becomes year zero). + 1BC becomes year zero).