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https://issues.apache.org/jira/browse/ARROW-637?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15931309#comment-15931309
]
Greg Rahn commented on ARROW-637:
---------------------------------
[~julianhyde] - Oracle has 3 timestamp types (from
https://docs.oracle.com/database/121/SQLRF/sql_elements001.htm#SQLRF0021)
* timestamp w/o time zone
* timestamp with local time zone
** Data is normalized to the database time zone when it is stored in the
database.
** When the data is retrieved, users see the data in the session time zone.
* timestamp with time zone
** Data is stored with an explicit time zone, but not adjusted/normalized for
local time zone.
** Value returned contains time zone offset information.
The ANSI and Oracle w/o TZ versions are the same, but the ANSI with TZ aligns
more to Oracle's with LOCAL TZ.
{noformat}
create table ts (
ts_string varchar(50),
ts_timestamp timestamp,
ts_timestamp_tz timestamp with time zone,
ts_timestamp_ltz timestamp with local time zone
);
insert into ts values (
'2016-01-01 00:00:00 +10:00',
timestamp '2016-01-01 00:00:00 +10:00',
timestamp '2016-01-01 00:00:00 +10:00',
timestamp '2016-01-01 00:00:00 +10:00'
);
alter session set NLS_TIMESTAMP_FORMAT = 'YYYY-MM-DD HH24:MI:SSXFF';
alter session set NLS_TIMESTAMP_TZ_FORMAT = 'YYYY-MM-DD HH24:MI:SSXFF TZR';
select dbtimezone from dual;
DBTIME
------
+00:00
select sessiontimezone from dual;
SESSIONTIMEZONE
---------------
-05:00
select * from ts;
TS_STRING TS_TIMESTAMP TS_TIMESTAMP_TZ
TS_TIMESTAMP_LTZ
-------------------------- --------------------------
--------------------------------- --------------------------
2016-01-01 00:00:00 +10:00 2016-01-01 00:00:00.000000 2016-01-01
00:00:00.000000 +10:00 2015-12-31 09:00:00.000000
{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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