Re: to_date()/to_timestamp() silently accept month=0 and day=0

On 23.04.26 17:40, Tom Lane wrote:
> Daniel Gustafsson <daniel(at)yesql(dot)se> writes:
>>> On 23 Apr 2026, at 09:57, Michael Paquier <michael(at)paquier(dot)xyz> wrote:
>>> Perhaps we could consider strengthening such inputs on HEAD once v20
>>> opens for business? It would be really a scary thing to backpatch,
>>> still a major release is a different thing.
>
>> This could definitely not be backpatched IMO, a quick check in v14 shows the
>> same behaviour. The gregorian calendar goes from BC1 to AD1 and does not
>> define a year 0, to_date('0000','YYYY') correctly returns year 0001, handling
>> months/days in the same way at least makes it consistent (though I didn't scour
>> the archives to see if it was intentionally done like that).
>
> Looking at the code, I think it intentionally interprets zero as
> "missing data". See for example the stanza at formatting.c:4650ff
> where tm_mon and tm_mday can be backfilled from a DDD field.
>
> I'm disinclined to change the behavior around this; you're far
> more likely to get complaints than kudos.

Complaints from whom? Oracle rejects these, and PostgreSQL generally
also rejects these dates/times in other contexts. I think this should
be rejected.