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.
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| | | [email protected] | -- Charles Stross, "Creative writing
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