arangosh> db.ids.ensureIndex({ type: "skiplist", fields: [ "name.first", "name.last" ], unique: true }); { "fields" : [ "name.first", "name.last" ], "id" : "ids/346902088", "sparse" : false, "type" : "skiplist", "unique" : true, "isNewlyCreated" : true, "code" : 201 } arangosh> db.ids.save({ "name" : { "first" : "hans", "last": "hansen" }}); { "_id" : "ids/347229768", "_rev" : "347229768", "_key" : "347229768" } arangosh> db.ids.save({ "name" : { "first" : "jens", "last": "jensen" }}); { "_id" : "ids/347426376", "_rev" : "347426376", "_key" : "347426376" } arangosh> db.ids.save({ "name" : { "first" : "hans", "last": "jensen" }}); { "_id" : "ids/347622984", "_rev" : "347622984", "_key" : "347622984" } arangosh> db.ids.save({ "name" : { "first" : "hans", "last": "hansen" }}); [ArangoError 1210: cannot create document, unique constraint violated]