1. I thought planet.osm is a snapshot, so I wonder why it then starts with a list of some changesets in front of nodes/ways/relations.

  2. planet.osm also does not look like the format specification at

https://wiki.openstreetmap.org/wiki/OSM_XML

but instead has changesets before the nodes.

asked 11 Jun '14, 07:40

snupo's gravatar image

snupo
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The canonical answer is likely: "because that is what the dump script does". Nobody claims that there is a rigourous definition of the file format nor that we are following it. The changesets do contain some extra information that could potentially be useful.

Given that our documentaion is on a wiki, the thing for you to do is to document the current practice.

http://wiki.openstreetmap.org/wiki/Planet.osm contains some more information on the dump process.

permanent link

answered 11 Jun '14, 08:21

SimonPoole's gravatar image

SimonPoole ♦
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accept rate: 19%

edited 11 Jun '14, 11:33

On the other hand including changesets in planet.osm could be a bug. And documenting which changesets will appear in the file and why they appear is not possible without knowing the dump script and the intention of its author.

(11 Jun '14, 08:37) scai ♦

that helps a bit, but you are playing it too loose for me. i still wonder if planet.osm a snapshot or not? now it is a yes/no question ;-) there must be a fairly strong oppinion on that, i believe.

(11 Jun '14, 08:38) snupo

@scai: I downloaded planet.osm from one of the links in the wiki, probably the first. do you mean that the weekly planet.osm's vary in their format? if so, is there any sort of "primary", or "authentical" data dump?

(11 Jun '14, 09:15) snupo
2

The code for the dumper is https://github.com/openstreetmap/planetdump (note there is a "NG" dumper used to produce the experimantal dumps that currently doesn't reside in the openstreetmap repository)

(11 Jun '14, 11:37) SimonPoole ♦

According to the code this behavior is configurable and changesets weren't contained in the past. So I guess the current behavior is intended.

@snupo No, that's not what I meant. There is only one planet dump.

(11 Jun '14, 11:57) scai ♦

The hint to the dumper-repo gives insight that TomH is the originator of the decision. While I know better why changesets are inside planet.osm, the question about the why remains open. I just do not understand what the sense of changesets inside a snapshot is - I thought changesets are deltas between snapshots, allowing to move from snapshot s1 to snapshot s2.

@simon: Would love to be contructive, but really do not feel in a position to update the wiki, in particular as I feel the information in the wiki makes good sense.

Anyway, can live well with ignoring the changesets.

(11 Jun '14, 12:30) snupo
1

@snupo ok that is a bit a different question, the changesets are a collection of edits of one user (roughly one editing session) see http://wiki.openstreetmap.org/wiki/Changeset for more information. They do not have any transactional or similar property.

What you may be thinking of are the diffs http://wiki.openstreetmap.org/wiki/Planet.osm/diffs , which -do- allow you, going forward, from a planet dump to follow the changes to the database.

(11 Jun '14, 12:57) SimonPoole ♦
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question asked: 11 Jun '14, 07:40

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