The user-provided data is arbitrary but not random. Certain keys like "name", "email", "browser", etc will show up very often, and might even be included automa

The user-provided data is arbitrary but not random. Certain keys like "name", "email", "browser", etc will show up very often, and might even be included automatically by the client-side libraries and therefore be present in almost all rows. There may be other values that only appear very rarely - say, "my_super_special_id", and you want to be able to support those as well.