Re: interval type additional option - Mailing list pgsql-hackers

From Andrew Gierth
Subject Re: interval type additional option
Date
Msg-id 87lg30aopg.fsf@news-spur.riddles.org.uk
Whole thread Raw
In response to interval type additional option  (Pavel Stehule <pavel.stehule@gmail.com>)
Responses Re: interval type additional option  (Pavel Stehule <pavel.stehule@gmail.com>)
List pgsql-hackers
>>>>> "Pavel" == Pavel Stehule <pavel.stehule@gmail.com> writes:

 Pavel> Hi
 Pavel> I have a value '400 days 30 sec':: interval

 Pavel> I don't understand why cast

 Pavel> postgres=# select '400days 30sec'::interval minute to second;

 ...

 Pavel> What is sense of this feature?
 
As far as I know it only exists because of the sql spec, and the
implementation has never been complete or working. I think it does
affect some input parsing cases, there are some nasty hacks here and
there to support it, but given that our intervals don't behave like the
spec's ones anyway, there seems to be little motivation to make it work
fully.

These work, for example:

select interval '4' year to month;  -- 4 months
select interval '4' hour;           -- 4 hours
select interval '4' hour to second; -- 4 seconds
select '4'::interval year to month; -- 4 months
etc.

-- 
Andrew (irc:RhodiumToad)


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