On Mon, Oct 25, 2010 at 2:44 PM, Jeff Davis <pg...@j-davis.com> wrote: > On Mon, 2010-10-25 at 14:11 -0400, Robert Haas wrote: >> On Mon, Oct 25, 2010 at 2:01 PM, Jeff Davis <pg...@j-davis.com> wrote: >> > On Mon, 2010-10-25 at 12:20 -0500, Kevin Grittner wrote: >> >> It would be very useful to be able to specify a granularity -- for >> >> example timestamps with a five minute granularity would be useful >> >> for scheduling appointments. In some cases the granularity might be >> >> inferred -- if we have a domain defined as numeric(13,2), it would >> >> be nice if the default granularity was 0.01::numeric. >> > >> > I don't think typmod really helps us much. It's more a property of the >> > column than the type. >> > >> > To specify different granularities, I don't think we can avoid >> > specifying new types with their own entries in pg_type. >> >> Why? > > Because typmod doesn't survive through a function call. Even if it did, > I don't think typmod has a real answer for type promotion, implicit > casting etc. > > If we lose the typmod (and therefore the granularity), then a function > like "adjacent" is difficult to answer if we use a closed-closed > canonical representation (as you suggested); and if we use a closed-open > representation then it's difficult to answer a question like whether a > range contains a specific timestamp. > > Can I turn the question around and ask how you intend to make it work > without new entries in pg_type?
Oh, maybe I'm confused. Are you saying you'd need multiple copies of the base type, or multiple range types based on a single base type? -- 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
