Should sparse fields prevent compound documents from showing?

Question

Given the following:

GET http://www.example.com/post/1?include=author

{
  "type": "post",
  "id": "1",
  "attributes": {
    "title": "It's a title.",
    "description": "It's a description."
  },
  "relationships": {
    "author": {
      "links": {
        "self": "http://example.com/articles/1/relationships/author",
        "related": "http://example.com/people?filter[article]=1"
      },
      "data":{
        "type":"people", "id":"9"
      }
    }
  },
  "included":[
    {
      "type":"people",
      "id": "9",
      "attributes": {
        "first-name": "Dan",
        "last-name": "Gebhardt",
        "twitter": "dgeb"
      },
      "links": {
        "self": "http://example.com/people/9"
      }
    }
  ],
  "links": {
    "self": "http://example.com/articles/1"
  }
}

If I were to append fields[post]=title, (i.e. GET http://www.example.com/post/1?include=author&fields[post]=title) should this prevent included (compound document) from displaying?

GET http://www.example.com/post/1?include=author&fields[post]=title

{
  "type": "post",
  "id": "1",
  "attributes": {
    "title": "It's a title.",
  },
  "relationships": {
    "author": {
      "links": {
        "self": "http://example.com/articles/1/relationships/author",
        "related": "http://example.com/people?filter[article]=1"
      },
      "data":{
        "type":"people", "id":"9"
      }
    }
  }
}

Or are compound documents still supposed to render?

Answer 1

Sparse Fieldsets and Compound Documents could be used together. The spec explicitly lists sparse fieldsets as the only allowed case in which a included resource may not be linked by another other resource in the same document:

** Compound Documents**

Compound documents require “full linkage”, meaning that every included resource MUST be identified by at least one resource identifier object in the same document. These resource identifier objects could either be primary data or represent resource linkage contained within primary or included resources.

The only exception to the full linkage requirement is when relationship fields that would otherwise contain linkage data are excluded via sparse fieldsets.

To directly answer your question: The spare fieldset should only affect the linkage between the resources (e.g. by not including the relationship field between them) but should not cause a resource to be not included that otherwise would.