Find list of CouchDB partition keys in small batches

getPartitions.js

const nano = require('Nano')(process.env.COUCH_URL)
const db = nano.db.use('pq')

// get list of partition keys
// Parameters:
// - startPartition - the last partition key you know about
// - limit - number of partition keys to getch
// Returns:
// - an array of partition keys
const getPartitions = async (startPartition = '', limit = 10) => {
  const partitions = []
  let currentPartition = startPartition
  // one API call per partition key required
  for (let i = 0; i < limit; i++) {
    // call GET /db/_all_docs?startkey="C:\uffff"&limit=1
    // to get first document of next partition
    const startkey = currentPartition + ':\uffff'
    const response = await db.list({ 
      startkey: startkey,
      limit: 1
    })
    
    // if no results, we're done
    if (response.rows.length === 0) {
      break
    }
    
    // extract partition key and use this as seed for next API call
    const p = response.rows[0].id.split(':')[0]
    partitions.push(p)
    currentPartition = p
  }
  return partitions
}

getPartitions('T',10).then(console.log)