arangosh> db.names.ensureIndex({ type: "persistent", fields: [ "first" ] }); { "deduplicate" : true, "fields" : [ "first" ], "id" : "names/18121", "isNewlyCreated" : true, "sparse" : false, "type" : "persistent", "unique" : false, "code" : 201 } arangosh> db.names.save({ "first" : "Tim" }); { "_id" : "names/18124", "_key" : "18124", "_rev" : "_WgE9RsS--_" } arangosh> db.names.save({ "first" : "Tom" }); { "_id" : "names/18128", "_key" : "18128", "_rev" : "_WgE9RsW--_" } arangosh> db.names.save({ "first" : "John" }); { "_id" : "names/18131", "_key" : "18131", "_rev" : "_WgE9Rse--_" } arangosh> db.names.save({ "first" : "Tim" }); { "_id" : "names/18134", "_key" : "18134", "_rev" : "_WgE9Rsi--_" } arangosh> db.names.save({ "first" : "Tom" }); { "_id" : "names/18137", "_key" : "18137", "_rev" : "_WgE9Rsm--_" }