title: Azure search service index pointing multiple document db collections
body: <p>How to load data from two separate collections of azure cosmos db to a single azure search index? I need a solution to join the data from two collections in a way similar to inner joining concept of SQL and load that data to azure search service.</p>
  
  <p>I have two collections in azure cosmos db.
  One for product and sample documents for the same is as below.</p>
  
  <pre><code>{
     "description": null,
     "links": [],
     "replaces": "00000000-0000-0000-0000-000000000000",
     "replacedBy": "00000000-0000-0000-0000-000000000000",
     "productTypeId": "ccd0bc73-c4a1-41bf-9c96-454a5ba1d025",
     "id": "a4853bf5-9c58-4fb5-a1ff-fc3ab575b4c8",
     "name": "New Product",
     "createDate": "2018-09-19T10:04:35.1951552Z",
     "createdBy": "00000000-0000-0000-0000-000000000000",
     "updateDate": "2018-10-05T13:46:24.7048358Z",
     "updatedBy": "DIJdyXMudaqeAdsw1SiNyJKRIi7Ktio5@clients"
   }
   {
     "description": null,
     "links": [],
     "replaces": "00000000-0000-0000-0000-000000000000",
     "replacedBy": "00000000-0000-0000-0000-000000000000",
     "productTypeId": "ccd0bc73-c4a1-41bf-9c96-454a5ba1d025",
     "id": "b9b6c3bc-a8f8-470f-ac93-be589eb1da16",
     "name": "New Product 2",
     "createDate": "2018-09-19T11:02:02.6919008Z",
     "createdBy": "00000000-0000-0000-0000-000000000000",
     "updateDate": "2018-09-19T11:02:02.6919008Z",
     "updatedBy": "00000000-0000-0000-0000-000000000000"
   }
   {
     "description": null,
     "links": [],
     "replaces": "00000000-0000-0000-0000-000000000000",
     "replacedBy": "00000000-0000-0000-0000-000000000000",
     "productTypeId": "ccd0bc73-c4a1-41bf-9c96-454a5ba1d025",
     "id": "98b3647a-3b40-4a00-bd0f-2a397bd48b68",
     "name": "New Product 7",
     "createDate": "2018-09-20T09:42:28.2913567Z",
     "createdBy": "00000000-0000-0000-0000-000000000000",
     "updateDate": "2018-09-20T09:42:28.2913567Z",
     "updatedBy": "00000000-0000-0000-0000-000000000000"
   }
  </code></pre>
  
  <p>Another collection for ProductType with below sample document.</p>
  
  <pre><code>{
    "description": null,
    "links": null,
    "replaces": "00000000-0000-0000-0000-000000000000",
    "replacedBy": "00000000-0000-0000-0000-000000000000",
    "id": "ccd0bc73-c4a1-41bf-9c96-454a5ba1d025",
    "name": "ProductType1_186",
    "createDate": "2018-09-18T23:54:43.9395245Z",
    "createdBy": "00000000-0000-0000-0000-000000000000",
    "updateDate": "2018-10-05T13:29:44.019851Z",
    "updatedBy": "DIJdyXMudaqeAdsw1SiNyJKRIi7Ktio5@clients"
  }
  </code></pre>
  
  <p>The product type id is referred in product collection and that is the column which links both the collections.</p>
  
  <p>I want to load the above two collections to the same azure search service index and I expect my field of index to be populated somewhat like below.</p>
  
  <p><a href="https://i.stack.imgur.com/YEMeJ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/YEMeJ.png" alt="enter image description here"></a></p>