MongoDB - Get collections, collection count, and size in MB

mongodbCollectionSizes.js

// Get the current timestamp in ISO 8601 format and adjust it to the desired format
var timestamp = new Date().toISOString().replace(/T/, ' ').replace(/\..+/, '');

// Print the header line for the CSV, including database name and timestamp
print("databaseName,timestamp,collectionName,documentCount,collectionSizeMB");

// Get the name of the current database
var dbName = db.getName();

// Get the list of all collection names in the current database
var collections = db.getCollectionNames();

// Iterate over each collection
collections.forEach(function(collectionName) {
    // Get the number of documents in the collection
    var count = db[collectionName].count();

    // Get the collection statistics
    var stats = db[collectionName].stats();
    var sizeInBytes = stats.size;
    var sizeInMB = sizeInBytes / 1024 / 1024;

    // Print the database name, timestamp, collection name, document count, and size in MB in CSV format
    print(dbName + "," + timestamp + "," + collectionName + "," + count + "," + sizeInMB);
});