Cursors and time limits

Go through large results in batches with a cursor and put a time limit on each query with maxTimeMS.

Requirements

• A connection with a user that has read on the database.

Go through in batches

const cursor = db.orders.find({ status: "paid" }).batchSize(500);
for await (const order of cursor) {
  handle(order);
}

The driver asks for each next batch with getMore to the same node that opened the cursor.

Put a time limit

db.orders.find({ status: "paid" }).maxTimeMS(2000);

Check

A query over the time limit fails with MaxTimeMSExpired (50) and stops keeping the node busy.

Common problems

• getMore fails with CursorNotFound (43) because the cursor expired, was closed or was asked of another node.

See also

• Sort and paginate
• Error codes