Kevin, On 03/07/2017 02:06 AM, Kevin Kenny wrote: > There are reasonable use cases for wanting to take a timezone name and > get back a multipolygon
Question is, does (the core database of) OSM have to fulfil these use cases! > or to get a list of name and multipolygon for > all the timezones (or all the timezones on a given map). That's hard to > do unless there are relations for the timezones. Not impossible, we > could query administrative boundaries for the tag, but that's likely to > be SLOW since the tag will at best be in hstore and not indexed. > Grouping disjoint items, such as "all the administrative regions in a > time zone" seems tailor-made for relations. In my opinion, no. We've been there - people (ab)using relations like some kind of bookmark, to make data retrieval easier (e.g. a relation "all cycleways in XY city" just because it was slow/difficult to retrieve them otherwise). You would typically use a relation to group things when they can be in more group than one, and therefore tagging the membership on the individual object becomes cumbersome - cycle, bus, or hiking routes are a prime example, since the same street/way can be part of several of them. Not so with time zones, I should hope; a region can only be associated with exactly one (not 0, not more than one) time zone. Hence adding a time zone tag to the object is the easiest way to maintain the data and to ensure that you don't accidentally have two! I agree it might make things a little more difficult for the consumer but an overpass query can quickly find every boundary relation tagged with a certain time zone, and I'm sure sooner or later specialist sites will take the data and prepare daily updated json files or whatever that one can overlay on a map. Bye Frederik -- Frederik Ramm ## eMail frede...@remote.org ## N49°00'09" E008°23'33" _______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging