[OSM-dev] Why are so many changeset so large?

[Eugene Alvin Villar]

Hi Alex,

What do you mean by "large"? Do you mean changesets that span a large
area (spanning whole continents)? Or changesets that have a lot of
objects modified (perhaps more than 1000)?

Based on the examples you provided, it seems you mean the former. Is
this correct?

Eugene


On Wed, Oct 17, 2012 at 7:04 AM, Alex Barth <alex at mapbox.com> wrote:
>
> I really like how activity streams shows easy-to-understand changes on the map using changemonger [1,2]. At the same time it creates an alternative break down of changes that is more granular than changesets. This diverts attention from _comments on changesets_. This is not ideal in my mind - these comments on changesets have great potential to become an even more important communication channel in the future.
>
> I understand activity streams / changemonger suggests a broken up view of data changes because many changesets are so large that they are effectively not meaningful. I'd like to understand better why these changesets are so large.
>
> Unscientifically digging back on the history of today, I'm seeing many many changesets that seem like they could be just as well much smaller - both in the sense of geographic extent and number of elements - I don't want to call anybody out here, but this is what I found:
>
> - http://www.openstreetmap.org/browse/changeset/13514072
> - http://www.openstreetmap.org/browse/changeset/13523015
> - http://www.openstreetmap.org/browse/changeset/13508818
>
> I understand that there will always be cases where a large changeset makes sense (e. g. bot changes), but it seems that we have many unnecessarily large changesets that make changesets a not very useful granularity for looking at data history.
>
> My questions
>
> - What are the recommendations for change set sizes?
> - Are there technical reasons why changesets should tend to be large? Are they expensive on some level?
> - Could editors encourage users to do more and smaller changesets?
> - What else could be done to encourage smaller changesets with meaningful comments?
>
> [1] http://lists.openstreetmap.org/pipermail/rails-dev/2012-October/001086.html
> [2] Click on 'activity' here http://suncobalt.dyndns.org:8081/?lat=51.61&lon=22.44&zoom=7&layers=M
>
> Alex Barth
> http://twitter.com/lxbarth
> tel (+1) 202 250 3633