Stefan de Konink wrote: > On Thu, 19 Mar 2009, Brett Henderson wrote: > > >> Osmosis will provide the capability to do this from 0.6 onwards. If >> disk space isn't an issue on the planet server I'll set it up as soon as >> I get time after 0.6 goes live. It has the ability to go back in time >> and produce full history diffs for any time interval in the same way it >> currently has the ability to produce delta diffs for any time interval. >> Again, if disk space isn't an issue I can create them for the life of OSM. >> > > You will query each changed object? Don't you think it would be nifty to > have these history tables before we move to 0.6? Instead of having now > half a year worth of planet files? > I'm not sure I understand your questions.
Osmosis already has the ability to produce changeset files for any point in time, the only issue is that it merges multiple changes for a single object into a single change. For example if a node gets modified twice in a given day, then only a single modification record will be written to the daily change file. The 0.6 mysql change reading task adds a new option that allows the full history for that period to be written to the change file. The code for querying the database is already proven and there is basically one query per table so it scales well. The history tables are indexed by timestamp and the query response times are proportional to the amount of data being read. So no, I won't query each changed object individually but yes I can extract every single change that has ever been made and produce what I *think* you're looking for. I don't understand your question about history tables. I'm not creating tables anywhere. If I dump complete history it will be into xml files that people can download and process as they please. Among other things it would let people visualise OSM changes over time with all data in a 0.6 format. As for having half a year worth of planet files, I'm not in any hurry to fix that particular problem. 0.6 should be out soon, and therefore I've only made changes to the 0.6 tasks and not the 0.5 tasks. Planet files have been around for several years now, another few months won't mean the end of the world. If somebody wishes to send me a patch to osmosis to extract full history from a 0.5 mysql database then I'll commit it. Brett _______________________________________________ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
