arangosh> db.ids.ensureIndex({ type: "skiplist", fields: [ "name.first", "name.last" ], unique: true }); { "deduplicate" : true, "fields" : [ "name.first", "name.last" ], "id" : "ids/18278", "isNewlyCreated" : true, "sparse" : false, "type" : "skiplist", "unique" : true, "code" : 201 } arangosh> db.ids.save({ "name" : { "first" : "hans", "last": "hansen" }}); { "_id" : "ids/18281", "_key" : "18281", "_rev" : "_WgE9YdC--_" } arangosh> db.ids.save({ "name" : { "first" : "jens", "last": "jensen" }}); { "_id" : "ids/18285", "_key" : "18285", "_rev" : "_WgE9YdG--_" } arangosh> db.ids.save({ "name" : { "first" : "hans", "last": "jensen" }}); { "_id" : "ids/18288", "_key" : "18288", "_rev" : "_WgE9YdK--_" } arangosh> db.ids.save({ "name" : { "first" : "hans", "last": "hansen" }}); [ArangoError 1210: unique constraint violated - in index 18278 of type skiplist over ["name.first","name.last"]; conflicting key: 18281]