Re: [openstreetmap/openstreetmap-website] Implement JSON support for the changeset download API (PR #5973)

2025-05-01 Thread Jochen Topf via rails-dev
joto left a comment (openstreetmap/openstreetmap-website#5973)

I could never understand why there are the `create`, `modify`, and `delete` 
actions in the osmChange format, or why there is an osmChange format at all. 
Why not use the format that the history file uses: A version 1 is a basically a 
create, any larger version a modify, if the `visible` flag is not set, it is a 
delete. Osmium has always handled it this way internally. Any implementation 
has to handle the case anyway that you get a `create` for something that's 
already there (which makes it into a `modify`) or some other corner cases like 
this.

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Re: [openstreetmap/openstreetmap-website] Implement JSON support for the changeset download API (PR #5973)

2025-05-16 Thread Jochen Topf via rails-dev
joto left a comment (openstreetmap/openstreetmap-website#5973)

> It seems there were good reasons to introduce it for the XML format back in 
> the days.

I don't think too much thought went into that decision at that time. It 
probably simply seemed a reasonable way to do things and it totally does make 
sense if you are thinking in terms of a "diff" file and not in terms of 
versioning. I am not sure about the timeline there, it might well be that we 
did not ship history files back then, so the idea of having a "visible" flag 
instead had not come up. I never thought about the file format until I had to 
implement it and found it more complex than it would need to be due to that 
extra level of hierarchy in the XML. And interestingly enough, we still only 
have change files in XML and not in PBF, because in PBF there would be no other 
way to format them than with that "visible" flag. (Side note: The [underlying 
software](https://github.com/openstreetmap/osmdbt) has supported creating PBF 
diffs for years now, they are just not used.)

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