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I am working on an analysis based on open data from a CKAN data store. For this analysis to be reproducible it obviously needs the exact same input dataset. I would hence like to make sure that a resource that is downloaded in a future execution of my analysis is the exact same resource of any current execution. For that CKAN would need to support revisions of resources, but I couldn't find such a mechanism. How does versioning of datasets and its resources work in CKAN and how do I know which part of the data and metadata will never change, and which part could change in the future?

  • not an answer to your question, but a workaround. why not save the ckan page and data link in the wayback machine? pointing to those will do what you want... – albert Mar 2 '17 at 13:51
  • Thanks for the hint, haven't heard of the wayback machine before, and that could be indeed a way to go. There are other workarounds, the easiest being packaging my analysis scripts with the downloaded data -- but that's exactly what I don't want to do: create redundant versions of the data set. Intuitively I expected CKAN to provide a permalink, but I might simply be wrong. – Tim Tröndle Mar 2 '17 at 14:02
  • i dunno about wrong....the need to version data has been a topic for awhile. dat data has recently released what looks to be the best way around that. hoping to see ckan adopt it. – albert Mar 2 '17 at 14:25
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Revisioning in CKAN is something that needs to be refactored and that is currently not exposed via the UI but internally objects are being revisioned and assigned a revision_id, including resources, that is accessible via the API.

See eg:

http://demo.ckan.org/api/3/action/package_show?id=8beb8f98-3a71-4615-a38d-6155f4b9153a http://demo.ckan.org/api/3/action/resource_show?id=fe507a10-4c49-4b18-8bf6-6705198cfd42

Also for uploaded files (not for resources that are linked to external sources) there is a last_modified timestamp added to the resource whenever the file is updated.

Would any of these be helpful?

  • I went through the API and I've seen these fields, but I am not exactly sure how to use them. I understand I can get a revision id / last modified timestamp. But is it possible to retrieve older revisions of a resource? If not, all I can do with the revision id / last modified timestamp is to acknowledge that the resource has changed in any possible way. – Tim Tröndle Mar 3 '17 at 11:10

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