Initially the user logs into a "zone", so when creating documents you know which collection they should go to. But on the user itself, then I only store the doc id's, without the collection. I guess I could store the collection as well, but that makes the structure a bit more nested. To explain the use case: 1. user logs into like slack community 1. 2. creates a doc, the doc is uploaded to community 1. 3. doc id is stored on the user (createdDocs:[ 'id1', 'id2' ]) So if a user name changes, then all ids for docs should be updated. I guess the solution would be to create a second map that includes the collections as well so: docInfo : { 'col1' : [ 'id1', 'id2' ], 'col2' : ['id3', 'id4'] }