arangosh> db.names.ensureIndex({ type: "persistent", fields: [ "first" ] }); { "deduplicate" : true, "fields" : [ "first" ], "id" : "names/15291", "isNewlyCreated" : true, "sparse" : false, "type" : "persistent", "unique" : false, "code" : 201 } arangosh> db.names.save({ "first" : "Tim" }); { "_id" : "names/15294", "_key" : "15294", "_rev" : "_VRerBuS---" } arangosh> db.names.save({ "first" : "Tom" }); { "_id" : "names/15298", "_key" : "15298", "_rev" : "_VRerBuS--_" } arangosh> db.names.save({ "first" : "John" }); { "_id" : "names/15301", "_key" : "15301", "_rev" : "_VRerBuW---" } arangosh> db.names.save({ "first" : "Tim" }); { "_id" : "names/15304", "_key" : "15304", "_rev" : "_VRerBuW--_" } arangosh> db.names.save({ "first" : "Tom" }); { "_id" : "names/15307", "_key" : "15307", "_rev" : "_VRerBua---" }