$dateSubtract
Reference group: Date expressions
What it does
Subtracts a date/time unit.
Syntax
{$dateSubtract: { startDate, unit, amount, timezone? }}
Use case
Rolling windows.
$dateSubtract: practical example
{ $set: { windowStart: { $dateSubtract: { startDate: "$$NOW", unit: "day", amount: 30 } } } }💡 Explanation
Subtracts a date/time unit.
When to use it
Rolling windows.
Key Takeaways
- Subtracts a date/time unit.
- Typical use: Rolling windows.