Walks through the records in a mongoose collection using a number of cursors

mongoose-walk.ts

const start_time = performance.now();
const count: number = 1000;

const wallets: Wallet[] = [];
const walletCount = await WalletModel.find({}).estimatedDocumentCount();

// create a cursor for every `currentIndex` documents in the collection
const getNthCursor = async (currentIndex: number) =>
  await WalletModel.find({ deleted_at: undefined }, { timeout: false })
    .lean()
    .limit(count)
    .skip(currentIndex * count)
    .sort({ balance: -1 })
    .cursor();

// map the cursors to be passed to `Promise.all()`
const cursorsPromises = [
  ...Array.from({ length: walletCount / count + 1 }).keys(),
].map(async (i: number) => await getNthCursor(i));

const cursors = await Promise.all(cursorsPromises);
const cursorMap = cursors.map(cursor =>
  cursor.eachAsync(wallet => wallets.push(wallet))
);

// execute cursors
await Promise.all(cursorMap);

const end_time = performance.now();
const duration = (end_time - start_time) / 1000;
console.log(duration)