Add sort and limit in customers batch

lib/customers.js

@@ -3,6 +3,7 @@ const uuid = require('uuid')
 const _ = require('lodash/fp')
 const BN = require('./bn')
 const anonymous = require('../lib/constants').anonymousCustomer
+const NUM_RESULTS = 20
 
 function add (customer) {
   const sql = 'insert into customers (id, phone, phone_at) values ($1, $2, now()) returning *'
@@ -34,8 +35,10 @@ function getDailyVolume (id) {
 }
 
 function batch () {
-  const sql = `select * from customers where id not in ($1)`
-  return db.any(sql, [anonymous.uuid])
+  const sql = `select * from customers 
+  where id != $1
+  order by created desc limit $2`
+  return db.any(sql, [ anonymous.uuid, NUM_RESULTS ])
 }
 
 module.exports = { add, get, batch }