values are implemented using floating-point numbers, microsecond precision is achieved for dates within a few years of 2000-01-01, but the precision degrades for dates further away.Note that using floating-point datetimes allows a larger range of standard requires.See Appendix B for the exact parsing rules of date/time input and for the recognized text fields including months, days of the week, and time zones. An input value that has an explicit time zone specified is converted to UTC using the appropriate offset for that time zone.
(In particular, and POSTGRES styles, day appears before month if DMY field ordering has been specified, otherwise month appears before day.
(See Section 8.5.1 for how this setting also affects interpretation of input values.) Table 8-15 shows an example.
Time zones, and time-zone conventions, are influenced by political decisions, not just earth geometry.
Time zones around the world became somewhat standardized during the 1900s, but continue to be prone to arbitrary changes, particularly with respect to daylight-savings rules.
uses the widely-used IANA (Olson) time zone database for information about historical time zone rules.