Message-ID: <0efbf18e-165e-4aae-97c1-2137201f0382@gmail.com>
Date: Mon, 16 Mar 2026 12:39:32 +0100
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Subject: Re: INTERVAL output format for iso_8601 is without dashes
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-docs@lists.postgresql.org
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From: =?UTF-8?Q?Benjamin_Kr=C3=B6ger?= <benjamin.kroeger@gmail.com>
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> PG Doc comments form <noreply@postgresql.org> writes:
>> https://www.postgresql.org/docs/current/datatype-datetime.html#DATATYPE-INTERVAL-OUTPUT
>> The output format for mixed Interval in style specification iso_8601 is
>> documented incorrectly.
>> The documentation says `P-1Y-2M3D​T-4H-5M-6S` while in reality there are no
>> dashes: `P1Y2M3D​T4H5M6S`
> 
> It looks correct to me:
> 
> regression=# set intervalstyle TO iso_8601;
> SET
> regression=# select '-1 year -2 mons +3 days -04:05:06'::interval;
>        interval
> ---------------------
>   P-1Y-2M3DT-4H-5M-6S
> (1 row)
> 
well, judging vom the columns `Year-Month Interval` and `Day-Time 
Interval` I didn't expect the input for the column `Mixed Interval` to 
have negative dimensions (since the other two are positive dimensions 
only). granted, I missed the positive three days :)

It might help to see the input values that led to the documented output 
values. If you look e.g. at the mixed interval output for style 
`postgres_verbose`, all dimensions are signed exactly opposite to the 
`iso_8601` style.