Hi All, The topic of getting access to bulk history data has come up a few times now so I'm wondering if people see a need for this.
Osmosis already provides the ability to produce a changeset of a specific time interval. This is currently being used to produce minute, hourly and daily changesets. By downloading and keeping all minute changesets it is possible to keep *most* history items but not all. The current osmosis extraction code looks at all the changes in an interval and collapses them into a single change. With minute changesets this is going to extract most individual history elements but not all. It would be fairly straightforward to modify osmosis to extract full history for a time interval. This could fit into the existing osmChange format without any modifications although clients might potentially have to make some changes to cope with multiple changes to a single id. Potentially the file extension should be modified from *.osc to something else like *.osh (history) to avoid confusion. With this functionality in place it would be straightforward to produce full history dumps to build a sequential set of history files for OSM. These files wouldn't be small but as a rough guesstimate the total size of all files would be less than double the existing planet dump. Similar daily, hourly and minute changesets could be produced to the existing changesets potentially replacing them over time. I didn't include full history in existing changesets because my main focus was to introduce the concept of distributed up-to-date OSM databases for secondary purposes such as rendering, routing, etc. This is starting to take off with OSMXAPI, ROMA, Mapnik's DB, etc. The next step is full history. As described above, this should be fairly simple to introduce with the 0.5 API. 0.6 introduces some nice things like explicit version numbers which will make correct ordered application of multiple changes to a database simpler, but replication of changeset information will require some changes to the osmChange format which I haven't put much thought into yet. Reactions? Brett _______________________________________________ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
