![]() Postgres=# insert into times values (' 10:15pm US/Eastern'::timestampandtz) Postgres=# create index ix_times_dt on times(dt) Postgres=# insert into times values (current_timestamp) īecause we have the time zone stored with the point-in-time timestamp, full btree indexing is supported (where the comparisons occur in UTC time, but values are preserved in local time zones). ![]() Postgres=# insert into times values (now()) Postgres=# create table times (dt timestampandtz) Using the standard set of casts support for now()/current_timestamp is preserved when using timestampandtz: Postgres=# select ' 10:15pm US/Eastern'::timestampandtz=' 7:15pm US/Pacific'::timestampandtz ?column? Postgres=# select ' 10:15pm'::timestamptz::timestampandtz timestampandtzĪll comparison operations are complete and act as point-in-time comparisons, so they are immutable (unlike timestamptz which relys on the current sesssion time zone): Postgres=# select ' 10:15pm'::timestamp::timestampandtz timestampandtz Postgres=# select ' 10:15pm US/Eastern'::timestampandtz::timestamptz timestamptzĬasts from timestamp are takes as a local timestamp converted to the session time zone: We convert our local timestamp to the UTC and the display routine for timestamptz takes over converting it to the local session timezone: Postgres=# select ' 10:15pm US/Eastern'::timestampandtz at time zone 'utc' timestampĬasts to timestamptz follow the same rules as normal timestamptz. Postgres=# select ' 10:15pm US/Eastern'::timestampandtz::timestamp timestamp ![]() Since the "at time zone" clause is also supported, the default, un-adorned conversion is to UTC: Cast to timestampĬasts to timestamp are always done from the local timestamp of the timestampandtz. ![]() The type supports casting from both timestamp and timestamptz and to both timestamp and timestamptz. The timezone IDs are fixed, and are simply a list of timezones from pg_timezone_names with each timezone assigned a specific fixed ID. The internal binary format of timestampandtz is 10 bytes with the standard 8-byte timestamp (in UTC) combines with a 2-byte timezone ID. You can see that the output is always the local time with the timezone displayed. Postgres=# select ' 10:15pm US/Pacific'::timestampandtz timestampandtz Using this format, the type also supports a forced timezone (doesn't matter what the session time zone is set to): The format for the input/output of direct timestampandtz is. Postgres=# select ' 10:15pm'::timestampandtz timestampandtz The standard timestamp date parsing is supported with the implicit session timezone: ![]() The type supports both input and output from text format both with a specified timezone and with the implicit session/database time zone. It is strange though that PostgreSQL rewrites the function used to create the index to a canonical form, but does not seem to do the same when the function is used in the WHERE clause (in order to match the index function).A postgresql date/time type that stores both the timestamp and the timezone. Index Cond: (date(timezone('UTC'::text, created_at)) = ''::date) > Bitmap Index Scan on foo_date_idx (cost.) Recheck Cond: (date(timezone('UTC'::text, created_at)) = ''::date) Postgres=> EXPLAIN SELECT * FROM foo WHERE DATE(TIMEZONE('UTC'::text, created_at)) = DATE('') Note that this is (and should be) functionally equivalent to DATE(created_at AT TIME ZONE 'UTC'), since the documentation says: The function timezone(zone, timestamp) is equivalent to the SQL-conforming construct timestamp AT TIME ZONE zone. Let's try to use the definition as stored by the database. +-+- date | date | date(timezone( 'UTC ':: text, created_at)) ![]()
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