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" }