Use Case

As a Node.js driver user performing using toArray on my cursors
I want to lower the cost of iterating through each document
So that I can get better performance from the API

This optimization exists in v3:
https://github.com/mongodb/node-mongodb-native/blob/v3.7.4/lib/cursor.js#L861-L864

User Impact

• Performance improvement

Dependencies

• All cursor usages but no functional change

Unknowns

• Internally representing the change in Typescript (can't remember what was meant by this)

Acceptance Criteria

Implementation Requirements

• Update toArray to:
  • consume entire batches as they arrive
  • use arrays returned from BSON to extend the local array being built
  • toArray can apply document transformations to the final array if a transform was given

Testing Requirements

• Sinon spy assert next is called less than # of documents

Additional Verification

• While working with the toArray and findManyAndExhaustCursor benchmarks. Change batchSize to NOT default to 1000, and rather remain unset. Document the change in results here, and file a follow up ticket in the Node v7 epic to consider changing that default.

Documentation Requirements

• None

Follow Up Requirements

• None