Find oldest/ youngest post in MongoDB collection?

To find oldest/youngest post in MongoDB collection, you can use sort() with limit(1). Use ascending sort (1) for oldest and descending sort (-1) for newest posts based on date fields.

Syntax

// For oldest post
db.collection.find().sort({"dateField": 1}).limit(1);

// For newest post  
db.collection.find().sort({"dateField": -1}).limit(1);

Sample Data

db.getOldestAndYoungestPostDemo.insertMany([
    {
        "UserId": "Larry@123",
        "UserName": "Larry", 
        "UserPostDate": new ISODate('2019-03-27 12:00:00')
    },
    {
        "UserId": "Sam@897",
        "UserName": "Sam",
        "UserPostDate": new ISODate('2012-06-17 11:40:30')
    },
    {
        "UserId": "David@777", 
        "UserName": "David",
        "UserPostDate": new ISODate('2018-01-31 10:45:35')
    },
    {
        "UserId": "Chris@909",
        "UserName": "Chris", 
        "UserPostDate": new ISODate('2017-04-14 04:12:04')
    }
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5c9a700f15e86fd1496b38ab"),
        ObjectId("5c9a703815e86fd1496b38ac"),
        ObjectId("5c9a705e15e86fd1496b38ad"),
        ObjectId("5c9a708915e86fd1496b38ae")
    ]
}

Example 1: Find Oldest Post

db.getOldestAndYoungestPostDemo.find().sort({"UserPostDate": 1}).limit(1);

{
    "_id": ObjectId("5c9a703815e86fd1496b38ac"),
    "UserId": "Sam@897", 
    "UserName": "Sam",
    "UserPostDate": ISODate("2012-06-17T11:40:30Z")
}

Example 2: Find Newest Post

db.getOldestAndYoungestPostDemo.find().sort({"UserPostDate": -1}).limit(1);

{
    "_id": ObjectId("5c9a700f15e86fd1496b38ab"),
    "UserId": "Larry@123",
    "UserName": "Larry", 
    "UserPostDate": ISODate("2019-03-27T12:00:00Z")
}

Key Points

• sort(1) arranges dates in ascending order (oldest first)
• sort(-1) arranges dates in descending order (newest first)
• limit(1) returns only the first document from sorted results

Conclusion

Use sort() with limit(1) to efficiently find oldest or newest posts. Sort ascending for oldest, descending for newest, and limit to one result for optimal performance.