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https://issues.apache.org/jira/browse/ARROW-637?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15930689#comment-15930689
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Greg Rahn commented on ARROW-637:
---------------------------------
Just to comment: most SQL implementations of {{TIMESTAMP WITH TIME ZONE}} do
not store timezone info (AFAIK, just Oracle's {{TIMESTAMP WITH TIME ZONE}}),
however, the data is normalized to UTC when stored. This means that a stored
value of 0 would return 1970-01-01 00:00 (or in PostgreSQL year 2000 since
their epoch is different than unix time) for a w/o timezone timestamp, but the
same value of 0 would return 1970-01-01 00:00Z adjusted for local time zone
settings if the type were "with time zone".
For example:
{noformat}
grahn=# create table ts (
grahn(# ts_string varchar(50),
grahn(# ts_timestamp timestamp without time zone,
grahn(# ts_timestamptz timestamp with time zone
grahn(# );
grahn=# insert into ts values (
grahn(# '2016-01-01 00:00:00+10'::varchar,
grahn(# '2016-01-01 00:00:00+10'::timestamp,
grahn(# '2016-01-01 00:00:00+10'::timestamptz
grahn(# );
grahn=# show timezone;
TimeZone
------------
US/Pacific
grahn=# select * from ts;
ts_string | ts_timestamp | ts_timestamptz
------------------------+---------------------+------------------------
2016-01-01 00:00:00+10 | 2016-01-01 00:00:00 | 2015-12-31 06:00:00-08
grahn=# set time zone 'Europe/Rome';
grahn=# show timezone;
TimeZone
-------------
Europe/Rome
grahn=# select * from ts;
ts_string | ts_timestamp | ts_timestamptz
------------------------+---------------------+------------------------
2016-01-01 00:00:00+10 | 2016-01-01 00:00:00 | 2015-12-31 15:00:00+01
{noformat}
> [Format] Add time zone metadata to Timestamp type
> -------------------------------------------------
>
> Key: ARROW-637
> URL: https://issues.apache.org/jira/browse/ARROW-637
> Project: Apache Arrow
> Issue Type: New Feature
> Components: Format
> Reporter: Wes McKinney
> Assignee: Wes McKinney
>
> As a metadata-only convenience, it would be useful to have an optional Olson
> time zone name or absolute time offset (e.g. {{+07:30}}) in the {{Timestamp}}
> flatbuffers type:
> https://github.com/apache/arrow/blob/master/format/Message.fbs#L94
> Null or length-0 string would indicate that the data is time zone naive, and
> shall not be considered to be localized.
> https://github.com/apache/arrow/pull/388
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