MongoDB Long Running Query

script.js

use mydb;
rs.secondaryOk();

db.Collection.aggregate([
    {
        $match: {
            groups: { $exists: true }
        }
    },
    {
        $group: {
            _id: {
                CustomerId: "$CustomerId",
            },
            groups: { $sum: { $size: "$Groups" } }
        }
    },
    {
        $match: {
            "countGroups": { $gt: 0 }
        }
    }
]).toArray();