$sum
Reference group: Accumulators and ranking
What it does
Sums numeric values; $sum: 1 counts group documents.
Syntax
{$sum: expression}
Use case
Totals and counts.
$sum: practical example
{ $group: { _id: "$status", count: { $sum: 1 }, revenue: { $sum: "$total" } } }💡 Explanation
Sums numeric values;
$sum: 1 counts group documents.
When to use it
Totals and counts.Key Takeaways
- Sums numeric values;
$sum: 1counts group documents. - Typical use: Totals and counts.