MongoDB # 索引 # 追加 > db.users.ensureIndex({ score: 1 }) { "createdCollectionAutomatically" : false, "numIndexesBefore" : 1, "numIndexesAfter" : 2, "ok" : 1 } # 一覧 > db.users.getIndexes() [ { "v" : 1, "key" : { "_id" : 1 }, "name" : "_…