On 2021-05-19 06:57:13 -0700, Adrian Klaver wrote: > On 5/18/21 11:31 PM, Bryn Llewellyn wrote: > > This seems to be at odds with what section “8.5.3. Time Zones” at > > > > https://www.postgresql.org/docs/current/datatype-datetime.html#DATATYPE-TIMEZONES <https://www.postgresql.org/docs/current/datatype-datetime.html#DATATYPE-TIMEZONES> > > > > says: > > > > « > > A time zone abbreviation, for example PST. Such a specification merely > > defines a particular offset from UTC, in contrast to full time zone > > names which can imply a set of daylight savings transition rules as > > well. The recognized abbreviations are listed in > > the pg_timezone_abbrevs view (see Section 51.91). You cannot set the > > configuration parameters TimeZone or log_timezone to a time zone > > abbreviation, but you can use abbreviations in date/time input values > > and with the AT TIME ZONE operator. > > » > > > > This claims (as I read it) that a time zone abbreviation uniquely > > determines an offset from UTC. > > It says no such thing Maybe that's the inherent ambiguity of the English language, but to me "Such a specification defines a particular offset from UTC" does imply a one-to-one mapping from abbreviation to offset. > and would be lying if it did. As far as pg_timezone_abbrevs is concerned, it is correct. abbrev is unique in that view: hjp=> select abbrev, count(*) from pg_timezone_abbrevs group by 1 having count(*) > 1; ╔════════╤═══════╗ ║ abbrev │ count ║ ╟────────┼───────╢ ╚════════╧═══════╝ (0 rows) (at least in PostgreSQL 11.12) It is not true in "the real world", where different time zones may use the same abbreviation. But that isn't what the paragraph is about. > What it is saying that, for example, the timezone America/Los_Angeles has > two timezone abbreviations PDT(what I'm currently in) and PST. If you use an > abbreviation you don't get the DST transition rules that a full timezone > name has. Yes, does also say that. hp -- _ | Peter J. Holzer | Story must make more sense than reality. |_|_) | | | | | hjp@xxxxxx | -- Charles Stross, "Creative writing __/ | http://www.hjp.at/ | challenge!"
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