如何在MongoDB未索引字段上有效运行复杂查询？
创建索引以有效运行复杂的查询。首先让我们创建一个包含文档的集合-
> db.demo400.insertOne({SubjectName:"Java Spring"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e610720fac4d418a0178572")
}
> db.demo400.insertOne({SubjectName:"Spring Hibernate"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e61072dfac4d418a0178573")
}
> db.demo400.insertOne({SubjectName:"Java Hibernate"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e610736fac4d418a0178574")
}
> db.demo400.createIndex({SubjectName:"text"});
{
"createdCollectionAutomatically" : false,
"numIndexesBefore" : 1,
"numIndexesAfter" : 2,
"ok" : 1
}在find()方法的帮助下显示集合中的所有文档-
> db.demo400.find();
这将产生以下输出-
{ "_id" : ObjectId("5e610720fac4d418a0178572"), "SubjectName" : "Java Spring" }
{ "_id" : ObjectId("5e61072dfac4d418a0178573"), "SubjectName" : "Spring Hibernate" }
{ "_id" : ObjectId("5e610736fac4d418a0178574"), "SubjectName" : "Java Hibernate" }以下是在未索引字段上有效执行复杂查询的查询-
> db.demo400.find({ $text: { $search: "Spring" } } )这将产生以下输出-
{ "_id" : ObjectId("5e61072dfac4d418a0178573"), "SubjectName" : "Spring Hibernate" }
{ "_id" : ObjectId("5e610720fac4d418a0178572"), "SubjectName" : "Java Spring" }