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Creating an index on a nested MongoDB field?
You can use dot(.) notation for this. Let us first create a collection with documents −
> db.createIndexOnNestedFieldDemo.insertOne(
{"UserDetails":{"UserPersonalDetails":{"UserFirstName":"John","UserLastName":"Smith"}}});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ce929c778f00858fb12e916")
}
>
> db.createIndexOnNestedFieldDemo.insertOne( {"UserDetails":{"UserPersonalDetails":{"UserFirstName":"Chris","UserLastName":"Brown"}}});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ce929d678f00858fb12e917")
}
> db.createIndexOnNestedFieldDemo.insertOne( {"UserDetails":{"UserPersonalDetails":{"UserFirstName":"David","UserLastName":"Miller"}}});
{
"acknowledged" : true,
"insertedId" : ObjectId("5ce929e378f00858fb12e918")
}Following is the query to display all documents from a collection with the help of find() method −
> db.createIndexOnNestedFieldDemo.find().pretty();
This will produce the following output −
{
"_id" : ObjectId("5ce929c778f00858fb12e916"),
"UserDetails" : {
"UserPersonalDetails" : {
"UserFirstName" : "John",
"UserLastName" : "Smith"
}
}
}
{
"_id" : ObjectId("5ce929d678f00858fb12e917"),
"UserDetails" : {
"UserPersonalDetails" : {
"UserFirstName" : "Chris",
"UserLastName" : "Brown"
}
}
}
{
"_id" : ObjectId("5ce929e378f00858fb12e918"),
"UserDetails" : {
"UserPersonalDetails" : {
"UserFirstName" : "David",
"UserLastName" : "Miller"
}
}
}Following is the query to create an index on a nested field −
>db.createIndexOnNestedFieldDemo.createIndex({"UserDetails.UserPersonalDetails.UserLastName":1});This will produce the following output −
{
"createdCollectionAutomatically" : false,
"numIndexesBefore" : 1,
"numIndexesAfter" : 2,
"ok" : 1
}
Updated on: 30-Jul-2019
1K+ Views
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