There is a pattern (Document Versioning Pattern) to use for when you want to explicitly keep many versions of the same documents. For example, let’s say a bank wants to keep track of the latest “conditions and rules” you agreed too, but wants to keep a history of the previous ones they sent you.
The Schema Versioning Pattern is used for when you have only one version of a document, but it may have a different shape than another document in the same collection. It may be OK to have different shapes, as your application can deal with these differences, or it may be a transitional phase where all documents will evolve from shape/version 2 to shape/version 3. That transition may take a fair amount of time and you may want to do the transition without downtime. In this scheme, all documents with “schema_version = 2” will have the exact same shape and forth on.
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