arangosh> db.ids.ensureIndex({ type: "skiplist", fields: [ "name.first", "name.last" ], unique: true }); { "deduplicate" : true, "fields" : [ "name.first", "name.last" ], "id" : "ids/16399", "isNewlyCreated" : true, "sparse" : false, "type" : "skiplist", "unique" : true, "code" : 201 } arangosh> db.ids.save({ "name" : { "first" : "hans", "last": "hansen" }}); { "_id" : "ids/16402", "_key" : "16402", "_rev" : "_XG3zInq--_" } arangosh> db.ids.save({ "name" : { "first" : "jens", "last": "jensen" }}); { "_id" : "ids/16406", "_key" : "16406", "_rev" : "_XG3zInq--B" } arangosh> db.ids.save({ "name" : { "first" : "hans", "last": "jensen" }}); { "_id" : "ids/16409", "_key" : "16409", "_rev" : "_XG3zInu--_" } [ArangoError 1210: unique constraint violated - in index 16399 of type skiplist over ["name.first","name.last"]; conflicting key: 16402]