如何提升 MongoDB 查询的执行速度?
mongodbdatabasebig data analytics
要提升查询的执行速度，可以使用索引并设置 unique: true。让我们创建一个包含文档的集合。
> db.demo193.createIndex({"LastName":1},{unique:true});
{
"createdCollectionAutomatically" : true,
"numIndexesBefore" : 1,
"numIndexesAfter" : 2,
"ok" : 1
}
> db.demo193.insertOne({"FirstName":"John","LastName":"Doe"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e3ade1803d395bdc21346d1")
}
> db.demo193.insertOne({"FirstName":"John","LastName":"Smith"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e3ade1f03d395bdc21346d2")
}
> db.demo193.insertOne({"FirstName":"David","LastName":"Miller"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e3ade2803d395bdc21346d3")
}
借助 find() 方法显示集合中的所有文档 −
> db.demo193.find();
这将产生以下输出 −
{ "_id" : ObjectId("5e3ade1803d395bdc21346d1"), "FirstName" : "John", "LastName" : "Doe" }
{ "_id" : ObjectId("5e3ade1f03d395bdc21346d2"), "FirstName" : "John", "LastName" : "Smith" }
{ "_id" : ObjectId("5e3ade2803d395bdc21346d3"), "FirstName" : "David", "LastName" : "Miller" }
以下查询旨在以更快的执行速度查找值 −
> db.demo193.find({"LastName":"Smith"});
这将产生以下输出 −
{ "_id" : ObjectId("5e3ade1f03d395bdc21346d2"), "FirstName" : "John", "LastName" : "Smith" }
