arangosh> db.ids.ensureIndex({ type: "skiplist", fields: [ "name.first", "name.last" ], unique: true }); { "deduplicate" : true, "fields" : [ "name.first", "name.last" ], "id" : "ids/74215", "isNewlyCreated" : true, "name" : "idx_1641835679939821570", "selectivityEstimate" : 1, "sparse" : false, "type" : "skiplist", "unique" : true, "code" : 201 } arangosh> db.ids.save({ "name" : { "first" : "hans", "last": "hansen" }}); { "_id" : "ids/74219", "_key" : "74219", "_rev" : "_ZG8Lmga---" } arangosh> db.ids.save({ "name" : { "first" : "jens", "last": "jensen" }}); { "_id" : "ids/74221", "_key" : "74221", "_rev" : "_ZG8Lmga--A" } arangosh> db.ids.save({ "name" : { "first" : "hans", "last": "jensen" }}); { "_id" : "ids/74223", "_key" : "74223", "_rev" : "_ZG8Lmge---" } arangosh> db.ids.save({ "name" : { "first" : "hans", "last": "hansen" }}); [ArangoError 1210: unique constraint violated - in index idx_1641835679939821570 of type skiplist over 'name.first, name.last'; conflicting key: 74219]