This ticket was split from DRIVERS-3009, please see that ticket for a detailed description.

Use Case

As a Node engineer
I want to run "findOne" commands optimally
So that the driver uses as little resources as possible to run this operation

FindOne is a common API that a lot of drivers implement. It is a corner case of a cursor returning command that the driver can be sure in advance it will only receive one batch and the cursor should be closed server-side before the firstBatch response returns.

(Why is this unique to find One? Even two documents can result in an unclosed cursor because each document can be equal to the max size forcing each to be returned in its own batch)

User Experience

• What is the desired/expected outcome for the user once this ticket is implemented?
• If bug: What is the number of impacted customers? How severe is the impact? Is anyone blocked or broken?

Dependencies

• upstream and/or downstream requirements and timelines to bear in mind

Risks/Unknowns

• What could go wrong while implementing this change? (e.g., performance, inadvertent behavioral changes in adjacent functionality, existing tech debt, etc)
• Is there an opportunity for better cross-driver alignment or testing in this area?
• Is there an opportunity to improve existing documentation on this subject?

Acceptance Criteria

Implementation Requirements

• Sync spec test changes and ensure findOne commands are built properly according to the clarifications made in the spec
• If possible investigate executing find as a "runCommand" instead of via a cursor.next() to avoid the overhead of cursor construction and cleanup.

Testing Requirements

• unit test, spec test sync, etc

Documentation Requirements

• DOCSP ticket, API docs, etc

Follow Up Requirements

• additional tickets to file, required releases, etc
• if node behavior differs/will differ from other drivers, confirm with dbx devs what standard to aim for and what plan, if any, exists to reconcile the diverging behavior moving forward