Re: Understanding years part of Interval

The years are converted to months and the fractional month is rounded half up:

        1.05 year = 12.6 month
        => 1 year 0.6 month
        => 1 year 1 month        (after rounding)

Compare that to 12.5 months to see when the rounding occurs:

        12.5 month / 12 month
        => 1.0416... years

Plug 1.0416 and 1.0417 into the interval to observe the rounding:

        =# select '1.0416 year'::interval, '1.0417 year'::interval;
         interval |   interval
        ----------+--------------
         1 year   | 1 year 1 mon

I understood what you explained, but cannot agree that it's correct.

Run these and you'll see the first and second select are fine, the third ... why ?

select distinct current_date + ((random()::numeric) * '1 year'::interval) from generate_series(1,100) order by 1;

select distinct current_date + ((random()::numeric) * '12 month'::interval) from generate_series(1,100) order by 1;
select distinct current_date + ((random()::numeric) || 'year')::interval from generate_series(1,100) order by 1;

So, I have to think ... never use fractional parts on years, right ?