On Wed, Aug 31, 2011 at 11:36 AM, Heikki Linnakangas <heikki.linnakan...@enterprisedb.com> wrote: > On 31.08.2011 18:09, Jeff Davis wrote: >> On Wed, 2011-08-31 at 09:20 +0300, Heikki Linnakangas wrote: >>> >>> On 31.08.2011 09:14, Jeff Davis wrote: >>>> >>>> First, a range is really a set. So if we take '[1,10)'::int4range and >>>> cast that to numrange, we end up moving from a set of exactly 9 elements >>>> to a set of an infinite number of elements. Going the other way is >>>> probably worse. >> ... >> >>> Can you only provide casts that make sense, like between int4 and >>> numeric range types, and leave out the ones that don't? >> >> There are certainly some casts that make sense, like >> int4range->int8range. Do you think int4range->numrange also makes sense? > > Not sure. It depends on whether you think of '[1,8]'::int4range as a finite > set of the integers between 1 and 8, or as a continuous range from 1 to 8. I > don't see harm in providing explicit casts like that, but I would be very > conservative with implicit and assignment casts.
+1 for that approach. It's really annoying when you can't explicitly cast between data types, and it might be that you just allow coercion via I/O functions since it's unlikely to be a performance-critical operation. But I can't see why you would want any implicit or assignment casts at all. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
