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Is MongoDB able to index a null value?
Yes, MongoDB can easily index a null value. Let us first create a collection with documents −
> db.demo170.createIndex({"Value":1},{unique:true});
{
"createdCollectionAutomatically" : true,
"numIndexesBefore" : 1,
"numIndexesAfter" : 2,
"ok" : 1
}
> db.demo170.insert({"Value":100});
WriteResult({ "nInserted" : 1 })
> db.demo170.insert({"Value":null});
WriteResult({ "nInserted" : 1 })
> db.demo170.insert({"Value":90});
WriteResult({ "nInserted" : 1 })
> db.demo170.insert({"Value":78});
WriteResult({ "nInserted" : 1 })Display all documents from a collection with the help of find() method −
> db.demo170.find();
This will produce the following output −
{ "_id" : ObjectId("5e369b789e4f06af551997da"), "Value" : 100 }
{ "_id" : ObjectId("5e369b7c9e4f06af551997db"), "Value" : null }
{ "_id" : ObjectId("5e369b809e4f06af551997dc"), "Value" : 90 }
{ "_id" : ObjectId("5e369b969e4f06af551997dd"), "Value" : 78 }Following is the query to index null −
> db.demo170.find().sort({Value:1});This will produce the following output −
{ "_id" : ObjectId("5e369b7c9e4f06af551997db"), "Value" : null }
{ "_id" : ObjectId("5e369b969e4f06af551997dd"), "Value" : 78 }
{ "_id" : ObjectId("5e369b809e4f06af551997dc"), "Value" : 90 }
{ "_id" : ObjectId("5e369b789e4f06af551997da"), "Value" : 100 }
Updated on: 01-Apr-2020
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