mongo相关操作

查看是否走索引

db.find(query).explain();

索引常用命令

查看当前索引状态

 db.collection.getIndexes();

创建普通的单列索引

db.collection.ensureIndex({field:1/-1});  //1是升续 2是降续

创建多列索引

db.collection.ensureIndex({field1:1/-1, field2:1/-1});

删除单个索引

db.collection.dropIndex({filed:1/-1});

删除所有索引

db.collection.dropIndexes();

创建唯一索引

db.collection.ensureIndex({filed.subfield:1/-1}, {unique:true});

嵌套查询

    {"devModel":"SC1200","fieldId":"201810101426402264","number":1,"seedFieldTypeId":"116","seedFieldTypeName":"配种舍",
    "sn":"866192031889460","timestamp":1544629680000,"type":"OUTDOOR_TEMPERATURE","value":-2.1,"warning":false}
    
    
    内层查询
    db.getCollection('data_manage').find({"sensorDataList.type":{"$in":["OUTDOOR_TEMPERATURE","NH3"]}})