From: | Vik Fearing <vik(at)postgresfriends(dot)org> |
---|---|
To: | Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
Subject: | Re: Add support for AT LOCAL |
Date: | 2023-06-06 08:24:55 |
Message-ID: | ef0aa5f1-8ea6-088c-3a3a-5804c12f79b1@postgresfriends.org |
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Lists: | pgsql-hackers |
On 6/6/23 03:56, Laurenz Albe wrote:
> On Mon, 2023-06-05 at 23:13 -0400, Vik Fearing wrote:
>> The Standard defines time zone conversion as follows:
>>
>> <datetime factor> ::=
>> <datetime primary> [ <time zone> ]
>>
>> <time zone> ::=
>> AT <time zone specifier>
>>
>> <time zone specifier> ::=
>> LOCAL
>> | TIME ZONE <interval primary>
>>
>>
>> While looking at something else, I noticed we do not support AT LOCAL.
>> The local time zone is defined as that of *the session*, not the server,
>> which can make this quite interesting in views where the view will
>> automatically adjust to the session's time zone.
>>
>> Patch against 3f1aaaa180 attached.
>
> +1 on the idea; it should be faily trivial, if not very useful.
Thanks.
> At a quick glance, it looks like you resolve "timezone" at the time
> the query is parsed. Shouldn't the resolution happen at query
> execution time?
current_setting(text) is stable, and my tests show that it is calculated
at execution time.
postgres=# prepare x as values (now() at local);
PREPARE
postgres=# set timezone to 'UTC';
SET
postgres=# execute x;
column1
----------------------------
2023-06-06 08:23:02.088634
(1 row)
postgres=# set timezone to 'Asia/Pyongyang';
SET
postgres=# execute x;
column1
----------------------------
2023-06-06 17:23:14.837219
(1 row)
Am I missing something?
--
Vik Fearing
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