Re: interval->day first cut

Michael,

> I've completed my first cut of adding a day field to the interval
> struct and patched up the regression tests for places where it failed
> due to the new behavior (e.g., interval '19:00' + interval '6:00' =
> interval '25:00'). I haven't added any regression tests for the DST
> behavior, but it works (and this could be the start of the regression
> tests). Note: DST changed on 2005-04-03:

This looks good so far.    I could have really used this for 2 calendar 
applicaitons, and *will* use it for my next one.  This is exactly the kind of 
behavior that calendar applications need.

> One interesting fallout of this is that adding two SQL-compliant
> intervals can produce non-SQL-compliant output:
>
> test=# select interval '3 days 16:39' + interval '1 day 15:32' as
> "interesting";
>     interesting
> -----------------
> 4 days 32:11:00

I personally don't have a problem with this if the my/dw/hms split is fully 
documented.   Does it put is in violation of the SQL spec, though?  If so, do 
we care?

Anyone know how Oracle/DB2 handles this? ( I know how MSSQL handles it -- 
badly.)

> I've added a interval_simplify function which assumes 1 day = 24
> hours and puts the interval in SQL-spec form. This could be exposed
> to let people "reduce" their intervals. However, I'm concerned this
> is surprising behavior.

Yes, well, we'll have to document it prominently in the release notes and 
elsewhere.   

-- 
Josh Berkus
Aglio Database Solutions
San Francisco