title: How to create composite partition key in documentdb
body: <p>This is how my document looks, I wanted to choose the partition key as /department/city; which is two different attribute, one form employee and another from address(which is an embedded object to employee). I tried give /department/address as partition key but it's not listing the partition key in data-explorer, I'm assuming it considering city is a attribute in department.</p>
  
  <pre><code>{
    "eid": "",
    "entryType": "",
    "address": 
    {
      "PIN": "",
      "city": "",
      "street": ""
    },
    "name": "",
    "id": "",
    "department": "",
    "age":
  }
  </code></pre>
  
  <p>Can you please help me understand what I'm doing wrong and how to design a composite partition  key and distribute/store/arrange employees data based on their department and city.</p>