How to migrate from carrierwave_backgrounder?

I am using carrierwave with an extension gem carrierwave_backgrounder.

One of my AR models has column image_processing
which stores whether “background processing is complete”.
(i.e. all the image versions, equivalent to Shrine’s “derivatives”, are generated)
(See carrierwave_backgrounder README to see original feature description)

I have implemented background promoting, and updated the worker to create derivatives before promote.
But I am not sure how to implement the feature mentioned above.
So I would like to hear your opinion.

Generally with Shrine’s backgrounding you don’t need a boolean column saying when processing is finished, you can just check the derivatives hash to see if the desired derivative is present. This is possible because Shrine saves data about processed derivatives into the attachment column (unlike CarrierWave or Paperclip).

Thanks for your reply.
I do understand the derivatives hash/info is saved into the data column.
However it’s bad for querying performance (even jsonb is used).
I am trying to avoid changes to other parts of the project.