diff --git a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php
index a85e313..8accff2 100644
--- a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php
+++ b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php
@@ -1022,6 +1022,7 @@ protected function processRevisionDataTable(ContentEntityTypeInterface $entity_t
   protected function processIdentifierSchema(&$schema, $key) {
     if ($schema['fields'][$key]['type'] == 'int') {
       $schema['fields'][$key]['type'] = 'serial';
+      $schema['fields'][$key]['not null'] = TRUE;
     }
     unset($schema['fields'][$key]['default']);
   }
@@ -1390,6 +1391,7 @@ protected function getSharedTableFieldSchema(FieldStorageDefinitionInterface $st
 
     $field_name = $storage_definition->getName();
     $field_description = $storage_definition->getDescription();
+    $base_table = $this->storage->getBaseTable();
 
     foreach ($column_mapping as $field_column_name => $schema_field_name) {
       $column_schema = $field_schema['columns'][$field_column_name];
@@ -1400,13 +1402,16 @@ protected function getSharedTableFieldSchema(FieldStorageDefinitionInterface $st
       $keys = $this->entityType->getKeys() + array('langcode' => 'langcode');
       // The label is an entity key, but label fields are not necessarily
       // required.
+      unset($keys['label']);
       // Because entity ID and revision ID are both serial fields in the base
       // and revision table respectively, the revision ID is not known yet, when
       // inserting data into the base table. Instead the revision ID in the base
       // table is updated after the data has been inserted into the revision
       // table. For this reason the revision ID field cannot be marked as NOT
       // NULL.
-      unset($keys['label'], $keys['revision']);
+      if ($table_name == $base_table) {
+        unset($keys['revision']);
+      }
       // In order to optimize indexes, forbid NULL values in Key fields. Other
       // columns necessarily allow NULL values in order to support adding a
       // base field definition to an entity type with non-empty base tables.
diff --git a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
index e0cae3c..328f2bd 100644
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
@@ -74,8 +74,7 @@ public static function propertyDefinitions(FieldStorageDefinitionInterface $fiel
       $target_id_definition = DataDefinition::create('string')
         ->setLabel(t('@label ID', array($target_type_info->getLabel())));
     }
-    // FIXME
-    // $target_id_definition->setRequired(TRUE);
+    $target_id_definition->setRequired(TRUE);
     $properties['target_id'] = $target_id_definition;
 
     $properties['entity'] = DataReferenceDefinition::create('entity')
diff --git a/core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageSchemaTest.php b/core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageSchemaTest.php
index 1d3bccb..1c6a2ef 100644
--- a/core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageSchemaTest.php
+++ b/core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageSchemaTest.php
@@ -256,72 +256,89 @@ public function testGetSchemaBase() {
             'description' => 'The name field.',
             'type' => 'varchar',
             'length' => 255,
+            'not null' => FALSE,
           ),
           'description__value' => array(
             'description' => 'The description field.',
             'type' => 'text',
+            'not null' => FALSE,
           ),
           'description__format' => array(
             'description' => 'The description field.',
             'type' => 'varchar',
+            'not null' => FALSE,
           ),
           'uuid' => array(
             'description' => 'The uuid field.',
             'type' => 'varchar',
             'length' => 128,
+            'not null' => FALSE,
           ),
           'hash' => array(
             'description' => 'The hash field.',
             'type' => 'varchar',
             'length' => 20,
+            'not null' => FALSE,
           ),
           'email__username' => array(
             'description' => 'The email field.',
             'type' => 'varchar',
+            'not null' => FALSE,
           ),
           'email__hostname' => array(
             'description' => 'The email field.',
             'type' => 'varchar',
+            'not null' => FALSE,
           ),
           'email__domain' => array(
             'description' => 'The email field.',
             'type' => 'varchar',
+            'not null' => FALSE,
           ),
           'owner' => array(
             'description' => 'The owner field.',
             'type' => 'int',
+            'not null' => FALSE,
           ),
           'translator' => array(
             'description' => 'The translator field.',
             'type' => 'int',
+            'not null' => FALSE,
           ),
           'location__country' => array(
             'description' => 'The location field.',
             'type' => 'varchar',
+            'not null' => FALSE,
           ),
           'location__state' => array(
             'description' => 'The location field.',
             'type' => 'varchar',
+            'not null' => FALSE,
           ),
           'location__city' => array(
             'description' => 'The location field.',
             'type' => 'varchar',
+            'not null' => FALSE,
           ),
           'editor' => array(
             'description' => 'The editor field.',
             'type' => 'int',
+            'not null' => FALSE,
           ),
           'editor_revision__target_id' => array(
             'description' => 'The editor_revision field.',
             'type' => 'int',
+            'not null' => FALSE,
           ),
           'editor_revision__target_revision_id' => array(
             'description' => 'The editor_revision field.',
             'type' => 'int',
+            'not null' => FALSE,
           ),
           'long_index_name' => array(
             'description' => 'The long_index_name field.',
             'type' => 'int',
+            'not null' => FALSE,
           ),
           'default_langcode' => array(
             'description' => 'Boolean indicating whether field values are in the default entity language.',
@@ -429,6 +446,7 @@ public function testGetSchemaRevisionable() {
           'revision_id' => array(
             'description' => 'The revision_id field.',
             'type' => 'int',
+            'not null' => FALSE,
           )
         ),
         'primary key' => array('id'),
@@ -454,6 +472,7 @@ public function testGetSchemaRevisionable() {
           'revision_id' => array(
             'description' => 'The revision_id field.',
             'type' => 'serial',
+            'not null' => TRUE,
           ),
         ),
         'primary key' => array('revision_id'),
@@ -661,6 +680,7 @@ public function testGetSchemaRevisionableTranslatable() {
           'revision_id' => array(
             'description' => 'The revision_id field.',
             'type' => 'serial',
+            'not null' => TRUE,
           ),
           'langcode' => array(
             'description' => 'The langcode field.',
@@ -691,6 +711,7 @@ public function testGetSchemaRevisionableTranslatable() {
           'revision_id' => array(
             'description' => 'The revision_id field.',
             'type' => 'int',
+            'not null' => FALSE,
           ),
           'langcode' => array(
             'description' => 'The langcode field.',
@@ -721,6 +742,7 @@ public function testGetSchemaRevisionableTranslatable() {
           'revision_id' => array(
             'description' => 'The revision_id field.',
             'type' => 'int',
+            'not null' => TRUE,
           ),
           'langcode' => array(
             'description' => 'The langcode field.',