Storing arbitrary key/value entries alongside a datomic entity

Say I have entities that I want to store in datomic. If the attributes are all known in advance, I just add them to my datomic schema once and can then make use of them.

What if in addition to known attributes, entities could have an arbitrary number of arbitrary keys, mapping to arbitrary values. Of course I can just store that list in some "blob" attribute that I also add to the schema, but then I couldn't easily query those attributes.

The solution that I've come up with is to define a key and a value attribute in datomic, each of type string , and treat every one of those additional key/value entries as entities in their own right, using aforementioned attributes. Then I can connect all those key/value-entities to the actual entity by means of a 1:n relation using the ref type.

That allows me to query. Is that the way to go or is there a better way?

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I would be reluctant to lose the power of attribute definitions. Datomic attributes can be added at any time, and the limit is reasonably high (2^20), so it may be reasonable to model the dynamic keys and values as they come along, creating a new attribute for each.

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