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Add a timezone-specific variant of date_trunc().

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date_trunc(field, timestamptz, zone_name) performs truncation using
the named time zone as reference, rather than working in the session
time zone as is the default behavior.  It's equivalent to

date_trunc(field, timestamptz at time zone zone_name) at time zone zone_name

but it's faster, easier to type, and arguably easier to understand.

Vik Fearing and Tom Lane

Discussion: https://postgr.es/m/6249ffc4-2b22-4c1b-4e7d-7af84fedd7c6@2ndquadrant.com
This commit is contained in:
Tom Lane
2018-11-14 15:41:07 -05:00
parent 06c723447b
commit 600b04d6b5
6 changed files with 166 additions and 27 deletions
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18
src/test/regress/expected/timestamptz.out
View File

@ -649,6 +649,24 @@ SELECT '' AS date_trunc_week, date_trunc( 'week', timestamp with time zone '2004
| Mon Feb 23 00:00:00 2004 PST
(1 row)
SELECT '' AS date_trunc_at_tz, date_trunc('day', timestamp with time zone '2001-02-16 20:38:40+00', 'Australia/Sydney') as sydney_trunc; -- zone name
date_trunc_at_tz | sydney_trunc
------------------+------------------------------
| Fri Feb 16 05:00:00 2001 PST
(1 row)
SELECT '' AS date_trunc_at_tz, date_trunc('day', timestamp with time zone '2001-02-16 20:38:40+00', 'GMT') as gmt_trunc; -- fixed-offset abbreviation
date_trunc_at_tz | gmt_trunc
------------------+------------------------------
| Thu Feb 15 16:00:00 2001 PST
(1 row)
SELECT '' AS date_trunc_at_tz, date_trunc('day', timestamp with time zone '2001-02-16 20:38:40+00', 'VET') as vet_trunc; -- variable-offset abbreviation
date_trunc_at_tz | vet_trunc
------------------+------------------------------
| Thu Feb 15 20:00:00 2001 PST
(1 row)
-- Test casting within a BETWEEN qualifier
SELECT '' AS "54", d1 - timestamp with time zone '1997-01-02' AS diff
FROM TIMESTAMPTZ_TBL

4
src/test/regress/sql/timestamptz.sql
View File

@ -193,6 +193,10 @@ SELECT '' AS "54", d1 - timestamp with time zone '1997-01-02' AS diff
SELECT '' AS date_trunc_week, date_trunc( 'week', timestamp with time zone '2004-02-29 15:44:17.71393' ) AS week_trunc;
SELECT '' AS date_trunc_at_tz, date_trunc('day', timestamp with time zone '2001-02-16 20:38:40+00', 'Australia/Sydney') as sydney_trunc; -- zone name
SELECT '' AS date_trunc_at_tz, date_trunc('day', timestamp with time zone '2001-02-16 20:38:40+00', 'GMT') as gmt_trunc; -- fixed-offset abbreviation
SELECT '' AS date_trunc_at_tz, date_trunc('day', timestamp with time zone '2001-02-16 20:38:40+00', 'VET') as vet_trunc; -- variable-offset abbreviation
-- Test casting within a BETWEEN qualifier
SELECT '' AS "54", d1 - timestamp with time zone '1997-01-02' AS diff
FROM TIMESTAMPTZ_TBL