diff --git a/packages/gatsby/src/redux/actions.js b/packages/gatsby/src/redux/actions.js
index 986c26bdb4c1e..ea083c25eeb90 100644
--- a/packages/gatsby/src/redux/actions.js
+++ b/packages/gatsby/src/redux/actions.js
@@ -748,8 +748,15 @@ actions.createNodeField = (
     node.fields = {}
   }
 
+  /**
+   * Normalized name of the field that will be used in schema
+   */
+  const schemaFieldName = _.includes(name, `___NODE`)
+    ? name.split(`___`)[0]
+    : name
+
   // Check that this field isn't owned by another plugin.
-  const fieldOwner = node.internal.fieldOwners[name]
+  const fieldOwner = node.internal.fieldOwners[schemaFieldName]
   if (fieldOwner && fieldOwner !== plugin.name) {
     throw new Error(
       stripIndent`
@@ -765,7 +772,7 @@ actions.createNodeField = (
 
   // Update node
   node.fields[name] = value
-  node.internal.fieldOwners[name] = plugin.name
+  node.internal.fieldOwners[schemaFieldName] = plugin.name
 
   return {
     type: `ADD_FIELD_TO_NODE`,
diff --git a/packages/gatsby/src/schema/__tests__/__snapshots__/data-tree-utils-test.js.snap b/packages/gatsby/src/schema/__tests__/__snapshots__/data-tree-utils-test.js.snap
index 76b3f2f9b1ea0..71992d1241589 100644
--- a/packages/gatsby/src/schema/__tests__/__snapshots__/data-tree-utils-test.js.snap
+++ b/packages/gatsby/src/schema/__tests__/__snapshots__/data-tree-utils-test.js.snap
@@ -55,7 +55,6 @@ Object {
     },
   },
   "date": "2006-07-22T22:39:53.000Z",
-  "emptyArray": null,
   "frontmatter": Object {
     "blue": 100,
     "circle": "happy",
@@ -64,7 +63,6 @@ Object {
     "title": "The world of dash and adventure",
   },
   "hair": 1,
-  "iAmNull": null,
   "key-with..unsupported-values": true,
   "name": "The Mad Max",
   "nestedArrays": Array [
diff --git a/packages/gatsby/src/schema/__tests__/data-tree-utils-test.js b/packages/gatsby/src/schema/__tests__/data-tree-utils-test.js
index fa1545ec17ad2..4f9ea17bc0c25 100644
--- a/packages/gatsby/src/schema/__tests__/data-tree-utils-test.js
+++ b/packages/gatsby/src/schema/__tests__/data-tree-utils-test.js
@@ -99,8 +99,8 @@ describe(`Gatsby data tree utils`, () => {
     expect(getExampleValues(nodes)).toMatchSnapshot()
   })
 
-  it(`null fields should have a null value`, () => {
-    expect(getExampleValues(nodes).iAmNull).toBeNull()
+  it(`skips null fields`, () => {
+    expect(getExampleValues(nodes).iAmNull).not.toBeDefined()
   })
 
   it(`should not mutate the nodes`, () => {
@@ -111,8 +111,8 @@ describe(`Gatsby data tree utils`, () => {
     expect(nodes[3].context.nestedObject.someOtherProperty).toEqual(3)
   })
 
-  it(`turns empty or sparse arrays to null`, () => {
-    expect(getExampleValues(nodes).emptyArray).toBeNull()
+  it(`skips empty or sparse arrays`, () => {
+    expect(getExampleValues(nodes).emptyArray).not.toBeDefined()
     expect(getExampleValues(nodes).hair).toBeDefined()
   })
 
@@ -156,11 +156,11 @@ describe(`Gatsby data tree utils`, () => {
   it(`skips unsupported types`, () => {
     // Skips functions
     let example = getExampleValues([{ foo: () => {} }])
-    expect(example.foo).toEqual(null)
+    expect(example.foo).not.toBeDefined()
 
     // Skips array of functions
     example = getExampleValues([{ foo: [() => {}] }])
-    expect(example.foo).toEqual(null)
+    expect(example.foo).not.toBeDefined()
   })
 })
 
diff --git a/packages/gatsby/src/schema/data-tree-utils.js b/packages/gatsby/src/schema/data-tree-utils.js
index e777db64c836d..b3abeb3a2aec2 100644
--- a/packages/gatsby/src/schema/data-tree-utils.js
+++ b/packages/gatsby/src/schema/data-tree-utils.js
@@ -153,34 +153,37 @@ const extractFieldExamples = (nodes: object[], selector: string) => {
   // get list of keys in all nodes
   const allKeys = _.uniq(_.flatten(nodes.map(_.keys)))
 
-  return _.zipObject(
-    allKeys,
-    allKeys.map(key => {
-      const nextSelector = selector && `${selector}.${key}`
-
-      const nodeWithValues = nodes.filter(node => {
-        if (!node) return false
-
-        const value = node[key]
-        if (_.isObject(value)) {
-          return !isEmptyObjectOrArray(value)
-        } else {
-          return isDefined(value)
-        }
+  return _.pickBy(
+    _.zipObject(
+      allKeys,
+      allKeys.map(key => {
+        const nextSelector = selector && `${selector}.${key}`
+
+        const nodeWithValues = nodes.filter(node => {
+          if (!node) return false
+
+          const value = node[key]
+          if (_.isObject(value)) {
+            return !isEmptyObjectOrArray(value)
+          } else {
+            return isDefined(value)
+          }
+        })
+
+        // we want to keep track of nodes as we need it to get origin of data
+        const entries = nodeWithValues.map(node => {
+          const value = node[key]
+          return {
+            value,
+            parent: node,
+            ...extractTypes(value),
+          }
+        })
+
+        return extractFromEntries(entries, nextSelector, key)
       })
-
-      // we want to keep track of nodes as we need it to get origin of data
-      const entries = nodeWithValues.map(node => {
-        const value = node[key]
-        return {
-          value,
-          parent: node,
-          ...extractTypes(value),
-        }
-      })
-
-      return extractFromEntries(entries, nextSelector, key)
-    })
+    ),
+    isDefined
   )
 }