Mongdb優化

1.索引
1)基礎索引
--爲集合colt1的x列創建升序基礎索引
# cd /usr/local/mongodb4.2.2/bin
# ./mongo -uroot -p
> use db_test
> db.colt1.find();
> db.colt1.getIndexes();
> db.colt1.ensureIndex({x:1});
> db.colt1.getIndexes();
--爲集合colt1的y列創建降序基礎索引
> db.colt1.ensureIndex({y:-1});
> db.colt1.getIndexes();
--通過後臺方式靜默爲colt1的y列創建升序索引,以免阻塞mongodb上的讀寫操作
> db.colt1.getIndexes();
> db.colt1.dropIndex("y_-1");
> db.colt1.getIndexes();
> db.colt1.ensureIndex({y:1},{background:true});
--查看當前活動的且運行時間超過3秒的後臺創建索引任務
> db.currentOp({"active":true,"secs_running":{ "$gt":3}});
--kill掉正在運行的任務
> db.killOp(opid)

2)文檔索引
--爲colt1中addr列創建文檔索引
> db.colt1.insert({x:"john",y:"student",addr:{country:"cn",city:"shanghai"}});
> db.colt1.find();
> db.colt1.ensureIndex({addr:1});
> db.colt1.getIndexes();
> db.colt1.find