arangosh> db.ids.ensureIndex({ type: "skiplist", fields: [ "name.first", "name.last" ], unique: true }); { "deduplicate" : true, "fields" : [ "name.first", "name.last" ], "id" : "ids/18633", "isNewlyCreated" : true, "sparse" : false, "type" : "skiplist", "unique" : true, "code" : 201 } arangosh> db.ids.save({ "name" : { "first" : "hans", "last": "hansen" }}); { "_id" : "ids/18636", "_key" : "18636", "_rev" : "_XGh_Z2C--_" } arangosh> db.ids.save({ "name" : { "first" : "jens", "last": "jensen" }}); { "_id" : "ids/18640", "_key" : "18640", "_rev" : "_XGh_Z2G--_" } arangosh> db.ids.save({ "name" : { "first" : "hans", "last": "jensen" }}); { "_id" : "ids/18643", "_key" : "18643", "_rev" : "_XGh_Z2K--_" } arangosh> db.ids.save({ "name" : { "first" : "hans", "last": "hansen" }}); [ArangoError 1210: unique constraint violated - in index 18633 of type skiplist over ["name.first","name.last"]; conflicting key: 18636]