From: | Artur Zakirov <zaartur(at)gmail(dot)com> |
---|---|
To: | John Naylor <john(dot)naylor(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | David Fetter <david(at)fetter(dot)org>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: truncating timestamps on arbitrary intervals |
Date: | 2020-03-19 08:20:55 |
Message-ID: | a389a68b-27f3-0554-3c5d-8f03a1dee530@gmail.com |
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Lists: | pgsql-hackers |
Hello,
On 3/13/2020 4:13 PM, John Naylor wrote:
> I've put off adding documentation on the origin piece pending comments
> about the approach.
>
> I haven't thought seriously about timezone yet, but hopefully it's
> just work and nothing to think too hard about.
Thank you for the patch. I looked it and tested a bit.
There is one interesting case which might be mentioned in the
documentation or in the tests is the following. The function has
interesting behaviour with real numbers:
=# select date_trunc_interval('0.1 year'::interval, TIMESTAMP
'2020-02-01 01:21:01');
date_trunc_interval
---------------------
2020-02-01 00:00:00
=# select date_trunc_interval('1.1 year'::interval, TIMESTAMP
'2020-02-01 01:21:01');
ERROR: only one interval unit allowed for truncation
It is because the second interval has two interval units:
=# select '0.1 year'::interval;
interval
----------
1 mon
=# select '1.1 year'::interval;
interval
--------------
1 year 1 mon
--
Artur
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