Hi All, With the recent discussions around deciding on file extensions (eg. osm, osc, osh, pbf, etc) it seemed a good time to raise a question I've had for a while now.
What is the relationship between osmChange (osc) files, and full history files (osh?) with visible attributes? When I first created the osc format for Osmosis, I also considered using the visible attribute approach. At the time I decided against it for a couple of reasons: - I wanted to avoid confusion about what type of data is contained in a file. - Code re-use and XML schema definition is more precise with osc because the node/way/relation elements are always the same without optional elements appearing in some formats and not others. - At the time I considered the visible flag attribute an aspect of our database implementation and not part of the OSM logical data model. I then used the osc file format to create not only the commonly used daily/hourly/minutely replication files, but also a complete dump of database history updated daily (stored in one file per day). http://planet.openstreetmap.org/history/ I was slightly surprised then to see the creation of the new full history files. Don't get me wrong, I don't have an issue with it and choice is good. But I do wonder why we've now gone back to a single massive file approach which is updated rarely and requires a full download each time when the existing files allow incremental download of recent changes. Merging all files into a single file can be done client-side if required without much processing overhead. It leaves me with a few questions: - Are the Osmosis-based daily full history extracts even used? Should I disable/delete them? - Are the history extracts in an unsuitable format and hence unused? - Should Osmosis switch over to using the osh format instead of osc to represent change data? - Does the full history single file contain additional useful data that is required? Changesets perhaps? What do people think? Cheers, Brett
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