arangosh> db.ids.ensureIndex({ type: "skiplist", fields: [ "name.first", "name.last" ], unique: true }); { "deduplicate" : true, "fields" : [ "name.first", "name.last" ], "id" : "ids/111551", "isNewlyCreated" : true, "sparse" : false, "type" : "skiplist", "unique" : true, "code" : 201 } arangosh> db.ids.save({ "name" : { "first" : "hans", "last": "hansen" }}); { "_id" : "ids/111554", "_key" : "111554", "_rev" : "_YOn1gLO--_" } arangosh> db.ids.save({ "name" : { "first" : "jens", "last": "jensen" }}); { "_id" : "ids/111558", "_key" : "111558", "_rev" : "_YOn1gLO--B" } arangosh> db.ids.save({ "name" : { "first" : "hans", "last": "jensen" }}); { "_id" : "ids/111561", "_key" : "111561", "_rev" : "_YOn1gLS--_" } arangosh> db.ids.save({ "name" : { "first" : "hans", "last": "hansen" }}); [ArangoError 1210: - in index 111551 of type skiplist over 'name.first, name.last'; conflicting key: 111554]