Example of how to create a row iterator using pg-cursor

pg-cursor iterator example.js

const createIterator = async sql => {
  const client = await pool.connect()
  const cursor = client.query(new Cursor(sql))
  const batchSize = 100

  return (async function getRows(client, cursor, batchSize) {
    let done = false

    // Get next rows
    const rows = await new Promise((resolve, reject) =>
      cursor.read(
        batchSize,
        (err, rows) => err ? reject(err) : resolve(rows)
      )
    )

    // Check if iteration is finished
    if (rows.length < 1) {
      done = true
      cursor.close(() => client.release())
    }

    // Return the iterator
    return {
      done,
      rows,
      next: async () => await getRows(client, cursor, batchSize)
    } 
  })(client, cursor, batchSize)
}

// Used like so:
let iterator = await createIterator ('select ... from ...')
while (!iterator.done) {
 let rows = iterator.rows
 // do stuff with rows
 iterator = await rowIterator.next()
}