arangosh> db.collection.ensureIndex({ type: "hash", fields: [ "_from", "type" ] })
{
"deduplicate" : true,
"fields" : [
"_from",
"type"
],
"id" : "collection/111679",
"isNewlyCreated" : true,
"selectivityEstimate" : 1,
"sparse" : false,
"type" : "hash",
"unique" : false,
"code" : 201
}