diff --git a/config/schema/search_api.index.schema.yml b/config/schema/search_api.index.schema.yml
index 6f7eb60..caf0fd2 100644
--- a/config/schema/search_api.index.schema.yml
+++ b/config/schema/search_api.index.schema.yml
@@ -35,23 +35,23 @@ search_api.index.*:
               label: 'The processor''s weight for this stage'
           settings:
             type: plugin.plugin_configuration.search_api_processor.[%parent.processor_id]
+    fields:
+      type: sequence
+      label: 'Indexed fields'
+      sequence:
+        type: mapping
+        label: field
+        mapping:
+          type:
+            type: string
+            label: 'Type of field'
+          boost:
+            type: float
+            label: 'Boost'
     options:
       type: mapping
       label: 'Options'
       mapping:
-        fields:
-          type: sequence
-          label: 'Indexed fields'
-          sequence:
-            type: mapping
-            label: field
-            mapping:
-              type:
-                type: string
-                label: 'Type of field'
-              boost:
-                type: float
-                label: 'Boost'
         additional fields:
           type: sequence
           label: 'Included additional fields'
diff --git a/search_api.api.php b/search_api.api.php
index 0fa2331..0c3fde8 100644
--- a/search_api.api.php
+++ b/search_api.api.php
@@ -152,7 +152,7 @@ function hook_search_api_query_alter(\Drupal\search_api\Query\QueryInterface &$q
     return;
   }
   // Otherwise, exclude the node with ID 10 from the search results.
-  $fields = $query->getIndex()->getFields();
+  $fields = $query->getIndex()->getCachedFields();
   foreach ($query->getIndex()->getDatasources() as $datasource_id => $datasource) {
     if ($datasource->getEntityTypeId() == 'node') {
       $field = \Drupal\search_api\Utility::createCombinedId($datasource_id, 'nid');
@@ -173,7 +173,7 @@ function hook_search_api_query_alter(\Drupal\search_api\Query\QueryInterface &$q
  */
 function hook_search_api_query_TAG_alter(\Drupal\search_api\Query\QueryInterface &$query) {
   // Exclude the node with ID 10 from the search results.
-  $fields = $query->getIndex()->getFields();
+  $fields = $query->getIndex()->getCachedFields();
   foreach ($query->getIndex()->getDatasources() as $datasource_id => $datasource) {
     if ($datasource->getEntityTypeId() == 'node') {
       $field = \Drupal\search_api\Utility::createCombinedId($datasource_id, 'nid');
diff --git a/search_api_db/search_api_db_defaults/config/optional/search_api.index.default_index.yml b/search_api_db/search_api_db_defaults/config/optional/search_api.index.default_index.yml
index 691992a..8c949e3 100644
--- a/search_api_db/search_api_db_defaults/config/optional/search_api.index.default_index.yml
+++ b/search_api_db/search_api_db_defaults/config/optional/search_api.index.default_index.yml
@@ -131,35 +131,35 @@ processors:
       fields:
         - rendered_item
         - 'entity:node/title'
+fields:
+  search_api_language:
+    type: string
+  'entity:node/title':
+    type: text
+    boost: 8
+  rendered_item:
+    type: text
+  'entity:node/created':
+    type: date
+  'entity:node/changed':
+    type: date
+  'entity:node/status':
+    type: boolean
+  'entity:node/sticky':
+    type: boolean
+  'entity:node/field_tags:entity:name':
+    type: string
+  'entity:node/uid:entity:name':
+    type: string
+  'entity:node/uid':
+    type: integer
+  search_api_node_grants:
+    type: string
+  'entity:node/type':
+    type: string
 options:
   index_directly: true
   cron_limit: 50
-  fields:
-    search_api_language:
-      type: string
-    'entity:node/title':
-      type: text
-      boost: 8
-    rendered_item:
-      type: text
-    'entity:node/created':
-      type: date
-    'entity:node/changed':
-      type: date
-    'entity:node/status':
-      type: boolean
-    'entity:node/sticky':
-      type: boolean
-    'entity:node/field_tags:entity:name':
-      type: string
-    'entity:node/uid:entity:name':
-      type: string
-    'entity:node/uid':
-      type: integer
-    search_api_node_grants:
-      type: string
-    'entity:node/type':
-      type: string
   'additional fields':
     'entity:node/field_tags': 'entity:node/field_tags'
     'entity:node/field_tags:entity': 'entity:node/field_tags:entity'
diff --git a/search_api_db/src/Plugin/search_api/backend/Database.php b/search_api_db/src/Plugin/search_api/backend/Database.php
index 2336a9e..39dc263 100644
--- a/search_api_db/src/Plugin/search_api/backend/Database.php
+++ b/search_api_db/src/Plugin/search_api/backend/Database.php
@@ -515,7 +515,7 @@ class Database extends BackendPluginBase {
       $this->getKeyValueStore()->set($index->id(), $db_info);
 
       // If there are no fields, we are done now.
-      if (!$index->getFields()) {
+      if (!$index->getCachedFields()) {
         return;
       }
     }
@@ -773,7 +773,7 @@ class Database extends BackendPluginBase {
     try {
       $db_info = $this->getIndexDbInfo($index);
       $fields = &$db_info['field_tables'];
-      $new_fields = $index->getFields();
+      $new_fields = $index->getCachedFields();
 
       $reindex = FALSE;
       $cleared = FALSE;
diff --git a/search_api_db/src/Tests/BackendTest.php b/search_api_db/src/Tests/BackendTest.php
index 725315a..a8409ab 100644
--- a/search_api_db/src/Tests/BackendTest.php
+++ b/search_api_db/src/Tests/BackendTest.php
@@ -159,13 +159,13 @@ class BackendTest extends EntityUnitTestBase {
     // Remove a field from the index and check if the change is matched in the
     // server configuration.
     $field_id = $this->getFieldId('keywords');
-    if (empty($index->getFields()[$field_id])) {
+    if (empty($index->getCachedFields()[$field_id])) {
       throw new \Exception();
     }
-    $index->getFields()[$field_id]->setIndexed(FALSE, TRUE);
+    $index->getCachedFields()[$field_id]->setIndexed(FALSE, TRUE);
     $index->save();
 
-    $index_fields = array_keys($index->getOption('fields', array()));
+    $index_fields = array_keys($index->getFields());
 
     $db_info = \Drupal::keyValue(BackendDatabase::INDEXES_KEY_VALUE_STORE_ID)->get($this->indexId);
     $server_fields = array_keys($db_info['field_tables']);
@@ -175,7 +175,7 @@ class BackendTest extends EntityUnitTestBase {
     $this->assertEqual($index_fields, $server_fields);
 
     // Add the field back for the next assertions.
-    $index->getFields(FALSE)[$field_id]->setIndexed(TRUE, TRUE);
+    $index->getCachedFields(FALSE)[$field_id]->setIndexed(TRUE, TRUE);
     $index->save();
   }
 
@@ -186,7 +186,7 @@ class BackendTest extends EntityUnitTestBase {
     /** @var \Drupal\search_api\IndexInterface $index */
     $index = $this->getIndex();
 
-    $index->getFields(FALSE)[$this->getFieldId('body')]->setIndexed(TRUE, TRUE);
+    $index->getCachedFields(FALSE)[$this->getFieldId('body')]->setIndexed(TRUE, TRUE);
 
     $processors = $index->getProcessorSettings();
     $processors['html_filter'] = array(
@@ -207,7 +207,7 @@ class BackendTest extends EntityUnitTestBase {
     $processors = $index->getProcessorSettings();
     unset($processors['html_filter']);
     $index->setProcessorSettings($processors);
-    $index->getFields()[$this->getFieldId('body')]->setIndexed(FALSE, TRUE);
+    $index->getCachedFields()[$this->getFieldId('body')]->setIndexed(FALSE, TRUE);
     $index->save();
   }
 
@@ -864,7 +864,7 @@ class BackendTest extends EntityUnitTestBase {
     /** @var \Drupal\search_api\IndexInterface $index */
     $index = $this->getIndex();
     $index->resetCaches();
-    $fields = $index->getFields(FALSE);
+    $fields = $index->getCachedFields(FALSE);
     $price_field = $fields[$this->getFieldId('prices')];
     $price_field->setType('decimal')->setIndexed(TRUE, TRUE);
     $success = $index->save();
@@ -910,7 +910,7 @@ class BackendTest extends EntityUnitTestBase {
     $this->assertEqual($count, 1, 'Indexing an item with an empty value for a non string field worked.');
 
     // Regression test for #2471509.
-    $index->getFields(FALSE)[$this->getFieldId('body')]->setIndexed(TRUE, TRUE);
+    $index->getCachedFields(FALSE)[$this->getFieldId('body')]->setIndexed(TRUE, TRUE);
     $index->save();
     $this->indexItems($this->indexId);
 
@@ -927,7 +927,7 @@ class BackendTest extends EntityUnitTestBase {
 
     // Regression test for #2616268.
     $index = $this->getIndex();
-    $index->getFields()[$this->getFieldId('body')]->setType('string', TRUE);
+    $index->getCachedFields()[$this->getFieldId('body')]->setType('string', TRUE);
     $index->save();
     $count = $this->indexItems($this->indexId);
     $this->assertEqual($count, 8, 'Switching type from text to string worked.');
@@ -940,7 +940,7 @@ class BackendTest extends EntityUnitTestBase {
     $this->assertIgnored($results);
     $this->assertWarnings($results);
 
-    $index->getFields()[$this->getFieldId('body')]->setIndexed(FALSE, TRUE);
+    $index->getCachedFields()[$this->getFieldId('body')]->setIndexed(FALSE, TRUE);
     $index->save();
   }
 
diff --git a/src/Entity/Index.php b/src/Entity/Index.php
index d814c8d..7763f02 100644
--- a/src/Entity/Index.php
+++ b/src/Entity/Index.php
@@ -201,12 +201,14 @@ class Index extends ConfigEntityBase implements IndexInterface {
    * @var \Drupal\search_api\Item\GenericFieldInterface[][][]|null
    *
    * @see computeFields()
-   * @see getFields()
+   * @see getCachedFields()
    * @see getFieldsByDatasource()
    * @see getAdditionalFields()
    * @see getAdditionalFieldsByDatasource()
    */
-  protected $fields;
+  protected $cachedFields;
+
+  protected $fields = array();
 
   /**
    * Cached fields data, grouped by datasource and indexed state.
@@ -354,6 +356,21 @@ class Index extends ConfigEntityBase implements IndexInterface {
   /**
    * {@inheritdoc}
    */
+  public function setFields(array $fields = array()) {
+    $this->fields = $fields;
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFields() {
+    return $this->fields;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
   public function isValidDatasource($datasource_id) {
     $datasources = $this->getDatasources();
     return !empty($datasources[$datasource_id]);
@@ -605,10 +622,10 @@ class Index extends ConfigEntityBase implements IndexInterface {
   /**
    * {@inheritdoc}
    */
-  public function getFields($only_indexed = TRUE) {
+  public function getCachedFields($only_indexed = TRUE) {
     $this->computeFields();
     $only_indexed = $only_indexed ? 1 : 0;
-    return $this->fields[$only_indexed]['fields'];
+    return $this->cachedFields[$only_indexed]['fields'];
   }
 
   /**
@@ -622,18 +639,18 @@ class Index extends ConfigEntityBase implements IndexInterface {
     // @todo Since labels and descriptions are translated, we probably need to
     //   cache per language?
     $cid = $this->getCacheId();
-    if (empty($this->fields)) {
+    if (empty($this->cachedFields)) {
       if ($cached = \Drupal::cache()->get($cid)) {
-        $this->fields = $cached->data;
-        if ($this->fields) {
-          $this->updateFieldsIndex($this->fields);
+        $this->cachedFields = $cached->data;
+        if ($this->cachedFields) {
+          $this->updateFieldsIndex($this->cachedFields);
         }
       }
     }
 
     // If not cached, fetch the list of fields and their properties.
-    if (empty($this->fields)) {
-      $this->fields = array(
+    if (empty($this->cachedFields)) {
+      $this->cachedFields = array(
         0 => array(
           'fields' => array(),
           'additional fields' => array(),
@@ -662,7 +679,7 @@ class Index extends ConfigEntityBase implements IndexInterface {
         $vars['%index'] = $this->label();
         \Drupal::logger('search_api')->warning('Warning while retrieving available fields for index %index: could not find a type mapping for the following fields: @fields.', $vars);
       }
-      \Drupal::cache()->set($cid, $this->fields, Cache::PERMANENT, $this->getCacheTags());
+      \Drupal::cache()->set($cid, $this->cachedFields, Cache::PERMANENT, $this->getCacheTags());
     }
   }
 
@@ -710,7 +727,7 @@ class Index extends ConfigEntityBase implements IndexInterface {
    */
   protected function convertPropertyDefinitionsToFields(array $properties, $datasource_id = NULL, $prefix = '', $label_prefix = '') {
     $type_mapping = Utility::getFieldTypeMapping();
-    $field_options = isset($this->options['fields']) ? $this->options['fields'] : array();
+    $field_options = $this->fields;
     $enabled_additional_fields = isset($this->options['additional fields']) ? $this->options['additional fields'] : array();
 
     // All field identifiers should start with the datasource ID.
@@ -774,12 +791,12 @@ class Index extends ConfigEntityBase implements IndexInterface {
           if ($original_property instanceof PropertyInterface) {
             $additional_field->setHidden($original_property->isHidden());
           }
-          $this->fields[0]['additional fields'][$key] = $additional_field;
+          $this->cachedFields[0]['additional fields'][$key] = $additional_field;
           if ($additional_field->isEnabled()) {
             while ($pos = strrpos($property_path, ':')) {
               $property_path = substr($property_path, 0, $pos);
               /** @var \Drupal\search_api\Item\AdditionalFieldInterface $additional_field */
-              $additional_field = $this->fields[0]['additional fields'][$property_path];
+              $additional_field = $this->cachedFields[0]['additional fields'][$property_path];
               $additional_field->setEnabled(TRUE);
               $additional_field->setLocked();
             }
@@ -838,7 +855,7 @@ class Index extends ConfigEntityBase implements IndexInterface {
         $field->setTypeLocked($original_property->isTypeLocked());
         $field->setHidden($original_property->isHidden());
       }
-      $this->fields[0]['fields'][$key] = $field;
+      $this->cachedFields[0]['fields'][$key] = $field;
       if (isset($field_options[$key]) || $field->isIndexedLocked()) {
         $field->setIndexed(TRUE);
         if (isset($field_options[$key])) {
@@ -847,7 +864,7 @@ class Index extends ConfigEntityBase implements IndexInterface {
             $field->setBoost($field_options[$key]['boost']);
           }
         }
-        $this->fields[1]['fields'][$key] = $field;
+        $this->cachedFields[1]['fields'][$key] = $field;
       }
     }
     foreach ($recurse as $arguments) {
@@ -858,8 +875,8 @@ class Index extends ConfigEntityBase implements IndexInterface {
     $sort_by_label = function(GenericFieldInterface $field1, GenericFieldInterface $field2) {
       return strnatcasecmp($field1->getLabel(), $field2->getLabel());
     };
-    uasort($this->fields[0]['fields'], $sort_by_label);
-    uasort($this->fields[0]['additional fields'], $sort_by_label);
+    uasort($this->cachedFields[0]['fields'], $sort_by_label);
+    uasort($this->cachedFields[0]['additional fields'], $sort_by_label);
   }
 
   /**
@@ -872,7 +889,7 @@ class Index extends ConfigEntityBase implements IndexInterface {
       $this->datasourceFields = array_fill_keys($this->datasources, array(array(), array()));
       $this->datasourceFields[NULL] = array(array(), array());
       /** @var \Drupal\search_api\Item\FieldInterface $field */
-      foreach ($this->fields[0]['fields'] as $field_id => $field) {
+      foreach ($this->cachedFields[0]['fields'] as $field_id => $field) {
         $this->datasourceFields[$field->getDatasourceId()][0][$field_id] = $field;
         if ($field->isIndexed()) {
           $this->datasourceFields[$field->getDatasourceId()][1][$field_id] = $field;
@@ -887,7 +904,7 @@ class Index extends ConfigEntityBase implements IndexInterface {
    */
   public function getAdditionalFields() {
     $this->computeFields();
-    return $this->fields[0]['additional fields'];
+    return $this->cachedFields[0]['additional fields'];
   }
 
   /**
@@ -899,7 +916,7 @@ class Index extends ConfigEntityBase implements IndexInterface {
       $this->datasourceAdditionalFields = array_fill_keys($this->datasources, array());
       $this->datasourceAdditionalFields[NULL] = array();
       /** @var \Drupal\search_api\Item\FieldInterface $field */
-      foreach ($this->fields[0]['additional fields'] as $field_id => $field) {
+      foreach ($this->cachedFields[0]['additional fields'] as $field_id => $field) {
         $this->datasourceAdditionalFields[$field->getDatasourceId()][$field_id] = $field;
       }
     }
@@ -914,8 +931,8 @@ class Index extends ConfigEntityBase implements IndexInterface {
     if (!isset($this->fulltextFields[$i])) {
       $this->fulltextFields[$i] = array();
       if ($only_indexed) {
-        if (isset($this->options['fields'])) {
-          foreach ($this->options['fields'] as $key => $field) {
+        if (isset($this->fields)) {
+          foreach ($this->fields as $key => $field) {
             if (Utility::isTextType($field['type'])) {
               $this->fulltextFields[$i][] = $key;
             }
@@ -923,7 +940,7 @@ class Index extends ConfigEntityBase implements IndexInterface {
         }
       }
       else {
-        foreach ($this->getFields(FALSE) as $key => $field) {
+        foreach ($this->getCachedFields(FALSE) as $key => $field) {
           if (Utility::isTextType($field->getType())) {
             $this->fulltextFields[$i][] = $key;
           }
@@ -1024,7 +1041,7 @@ class Index extends ConfigEntityBase implements IndexInterface {
     if (!$this->status) {
       throw new SearchApiException(new FormattableMarkup("Couldn't index values on index %index (index is disabled)", array('%index' => $this->label())));
     }
-    if (empty($this->options['fields'])) {
+    if (empty($this->fields)) {
       throw new SearchApiException(new FormattableMarkup("Couldn't index values on index %index (no fields selected)", array('%index' => $this->label())));
     }
 
@@ -1192,6 +1209,7 @@ class Index extends ConfigEntityBase implements IndexInterface {
     $this->datasourcePlugins = NULL;
     $this->trackerPlugin = NULL;
     $this->serverInstance = NULL;
+    $this->cachedFields = NULL;
     $this->fields = NULL;
     $this->datasourceFields = NULL;
     $this->fulltextFields = NULL;
@@ -1257,15 +1275,15 @@ class Index extends ConfigEntityBase implements IndexInterface {
         if ($property instanceof PropertyInterface && $property->isIndexedLocked()) {
           $settings = $property->getFieldSettings();
           // Don't overwrite settings that aren't locked (like the boost).
-          if (isset($this->options['fields'][$key])) {
-            $settings += $this->options['fields'][$key];
+          if (isset($this->fields[$key])) {
+            $settings += $this->fields[$key];
           }
           if (empty($settings['type']) || $property->isTypeLocked()) {
             $mapping = Utility::getFieldTypeMapping();
             $type = $property->getDataType();
             $settings['type'] = !empty($mapping[$type]) ? $mapping[$type] : 'string';
           }
-          $this->options['fields'][$key] = $settings;
+          $this->fields[$key] = $settings;
           $change = TRUE;
         }
       }
@@ -1555,7 +1573,7 @@ class Index extends ConfigEntityBase implements IndexInterface {
     unset($properties['datasourcePlugins']);
     unset($properties['trackerPlugin']);
     unset($properties['serverInstance']);
-    unset($properties['fields']);
+    unset($properties['cachedFields']);
     unset($properties['datasourceFields']);
     unset($properties['fulltextFields']);
     unset($properties['processors']);
diff --git a/src/Form/IndexFieldsForm.php b/src/Form/IndexFieldsForm.php
index bb56cc6..1ee223f 100644
--- a/src/Form/IndexFieldsForm.php
+++ b/src/Form/IndexFieldsForm.php
@@ -106,6 +106,8 @@ class IndexFieldsForm extends EntityForm {
   public function buildForm(array $form, FormStateInterface $form_state) {
     $index = $this->entity;
 
+    debug($index->getFields());
+
     // Set an appropriate page title.
     $form['#title'] = $this->t('Manage fields for search index %label', array('%label' => $index->label()));
     $form['#tree'] = TRUE;
@@ -256,7 +258,7 @@ class IndexFieldsForm extends EntityForm {
     // Store the fields configuration.
     $values = $form_state->getValues();
     $fields = $values['fields'];
-    foreach ($index->getFields(FALSE) as $field_id => $field) {
+    foreach ($index->getCachedFields(FALSE) as $field_id => $field) {
       if (isset($fields[$field_id])) {
         $field->setType($fields[$field_id]['type']);
         $field->setBoost($fields[$field_id]['boost']);
diff --git a/src/IndexInterface.php b/src/IndexInterface.php
index 78f9d3b..03c2674 100644
--- a/src/IndexInterface.php
+++ b/src/IndexInterface.php
@@ -132,6 +132,9 @@ interface IndexInterface extends ConfigEntityInterface {
    */
   public function getDatasourceIds();
 
+  public function getFields();
+  public function setFields(array $fields);
+
   /**
    * Determines whether the given datasource ID is valid for this index.
    *
@@ -336,7 +339,7 @@ interface IndexInterface extends ConfigEntityInterface {
    *   An array of all known (or indexed, if $only_indexed is TRUE) fields for
    *   this index, keyed by field identifier.
    */
-  public function getFields($only_indexed = TRUE);
+  public function getCachedFields($only_indexed = TRUE);
 
   /**
    * Returns a list of all known fields of a specific datasource.
diff --git a/src/Item/Field.php b/src/Item/Field.php
index 0660ca7..3039aef 100644
--- a/src/Item/Field.php
+++ b/src/Item/Field.php
@@ -79,10 +79,10 @@ class Field implements \IteratorAggregate, FieldInterface {
   public function setType($type, $notify = FALSE) {
     $this->type = $type;
     if ($notify) {
-      $fields = $this->index->getOption('fields', array());
+      $fields = $this->index->getFields();
       if (isset($fields[$this->fieldIdentifier])) {
         $fields[$this->fieldIdentifier]['type'] = $type;
-        $this->index->setOption('fields', $fields);
+        $this->index->setFields($fields);
       }
     }
     return $this;
@@ -140,7 +140,7 @@ class Field implements \IteratorAggregate, FieldInterface {
    */
   public function isIndexed() {
     if (!isset($this->indexed)) {
-      $fields = $this->index->getOption('fields', array());
+      $fields = $this->index->getFields();
       $this->indexed = isset($fields[$this->fieldIdentifier]);
     }
     return $this->isIndexedLocked() || $this->indexed;
@@ -152,7 +152,7 @@ class Field implements \IteratorAggregate, FieldInterface {
   public function setIndexed($indexed, $notify = FALSE) {
     $this->indexed = (bool) $indexed;
     if ($notify) {
-      $fields = $this->index->getOption('fields', array());
+      $fields = $this->index->getFields();
       if ($indexed) {
         $fields[$this->fieldIdentifier] = array('type' => $this->getType());
         if (($boost = $this->getBoost()) != 1.0) {
@@ -162,7 +162,7 @@ class Field implements \IteratorAggregate, FieldInterface {
       else {
         unset($fields[$this->fieldIdentifier]);
       }
-      $this->index->setOption('fields', $fields);
+      $this->index->setFields($fields);
     }
     return $this;
   }
@@ -172,7 +172,7 @@ class Field implements \IteratorAggregate, FieldInterface {
    */
   public function getBoost() {
     if (!isset($this->boost)) {
-      $fields = $this->index->getOption('fields', array());
+      $fields = $this->index->getFields();
       $this->boost = isset($fields[$this->fieldIdentifier]['boost']) ? (float) $fields[$this->fieldIdentifier]['boost'] : 1.0;
     }
     return $this->boost;
@@ -185,7 +185,7 @@ class Field implements \IteratorAggregate, FieldInterface {
     $boost = (float) $boost;
     $this->boost = $boost;
     if ($notify) {
-      $fields = $this->index->getOption('fields', array());
+      $fields = $this->index->getFields();
       if (isset($fields[$this->fieldIdentifier])) {
         if ($boost != 1.0) {
           $fields[$this->fieldIdentifier]['boost'] = $boost;
@@ -193,7 +193,7 @@ class Field implements \IteratorAggregate, FieldInterface {
         else {
           unset($fields[$this->fieldIdentifier]['boost']);
         }
-        $this->index->setOption('fields', $fields);
+        $this->index->setFields($fields);
       }
     }
     return $this;
diff --git a/src/Plugin/search_api/datasource/ContentEntity.php b/src/Plugin/search_api/datasource/ContentEntity.php
index 3c53b91..db1a129 100644
--- a/src/Plugin/search_api/datasource/ContentEntity.php
+++ b/src/Plugin/search_api/datasource/ContentEntity.php
@@ -868,7 +868,7 @@ class ContentEntity extends DatasourcePluginBase {
     // @todo This should definitely be the responsibility of the index class,
     //   this is nothing specific to the datasource.
     $fields = array();
-    foreach ($this->getIndex()->getFields() as $field) {
+    foreach ($this->getIndex()->getCachedFields() as $field) {
       if ($field->getDatasourceId() === $this->pluginId) {
         $fields[] = $field->getPropertyPath();
       }
diff --git a/src/Plugin/search_api/processor/AggregatedFields.php b/src/Plugin/search_api/processor/AggregatedFields.php
index e981379..8dba920 100644
--- a/src/Plugin/search_api/processor/AggregatedFields.php
+++ b/src/Plugin/search_api/processor/AggregatedFields.php
@@ -105,7 +105,7 @@ class AggregatedFields extends ProcessorPluginBase {
     $types = $this->getTypes();
 
     // Get the available fields for this index.
-    $fields = $this->index->getFields(FALSE);
+    $fields = $this->index->getCachedFields(FALSE);
     $field_options = array();
     $field_properties = array();
 
@@ -399,7 +399,7 @@ class AggregatedFields extends ProcessorPluginBase {
     }
     $types = $this->getTypes('type');
     if (isset($this->configuration['fields'])) {
-      $index_fields = $this->index->getFields(FALSE);
+      $index_fields = $this->index->getCachedFields(FALSE);
       foreach ($this->configuration['fields'] as $field_id => $field) {
         $definition = array(
           'label' => $field['label'],
diff --git a/src/Plugin/search_api/processor/Highlight.php b/src/Plugin/search_api/processor/Highlight.php
index c6d154b..1d2372a 100644
--- a/src/Plugin/search_api/processor/Highlight.php
+++ b/src/Plugin/search_api/processor/Highlight.php
@@ -237,7 +237,7 @@ class Highlight extends ProcessorPluginBase {
 
     // All the index's fulltext fields, grouped by datasource.
     $fulltext_fields = array();
-    foreach ($this->index->getFields() as $field_id => $field) {
+    foreach ($this->index->getCachedFields() as $field_id => $field) {
       if (Utility::isTextType($field->getType())) {
         $fulltext_fields[$field->getDatasourceId()][$field_id] = $field;
       }
diff --git a/src/Plugin/views/argument/SearchApiFulltext.php b/src/Plugin/views/argument/SearchApiFulltext.php
index 44b939c..d197998 100644
--- a/src/Plugin/views/argument/SearchApiFulltext.php
+++ b/src/Plugin/views/argument/SearchApiFulltext.php
@@ -118,7 +118,7 @@ class SearchApiFulltext extends SearchApiArgument {
       return array();
     }
 
-    $fields_info = $index->getFields();
+    $fields_info = $index->getCachedFields();
     foreach ($index->getFulltextFields() as $field_id) {
       $fields[$field_id] = $fields_info[$field_id]->getPrefixedLabel();
     }
diff --git a/src/Plugin/views/argument/SearchApiMoreLikeThis.php b/src/Plugin/views/argument/SearchApiMoreLikeThis.php
index f1da51f..4b777ba 100644
--- a/src/Plugin/views/argument/SearchApiMoreLikeThis.php
+++ b/src/Plugin/views/argument/SearchApiMoreLikeThis.php
@@ -79,7 +79,7 @@ class SearchApiMoreLikeThis extends SearchApiArgument {
       }
       $fields = isset($this->options['fields']) ? $this->options['fields'] : array();
       if (!$fields) {
-        foreach ($this->query->getIndex()->getOption('fields', array()) as $key => $field) {
+        foreach ($this->query->getIndex()->getFields() as $key => $field) {
           $fields[] = $key;
         }
       }
diff --git a/src/Processor/FieldsProcessorPluginBase.php b/src/Processor/FieldsProcessorPluginBase.php
index 340a4ab..b00b70d 100644
--- a/src/Processor/FieldsProcessorPluginBase.php
+++ b/src/Processor/FieldsProcessorPluginBase.php
@@ -47,7 +47,7 @@ abstract class FieldsProcessorPluginBase extends ProcessorPluginBase {
   public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
     $form = parent::buildConfigurationForm($form, $form_state);
 
-    $fields = $this->index->getFields();
+    $fields = $this->index->getCachedFields();
     $field_options = array();
     $default_fields = array();
     if (isset($this->configuration['fields'])) {
@@ -223,7 +223,7 @@ abstract class FieldsProcessorPluginBase extends ProcessorPluginBase {
    *   passed by reference.
    */
   protected function processConditions(array &$conditions) {
-    $fields = $this->index->getFields();
+    $fields = $this->index->getCachedFields();
     foreach ($conditions as $key => &$condition) {
       if ($condition instanceof ConditionInterface) {
         $field = $condition->getField();
diff --git a/src/Tests/CustomDataTypesUnitTest.php b/src/Tests/CustomDataTypesUnitTest.php
index d75662e..829dbb3 100644
--- a/src/Tests/CustomDataTypesUnitTest.php
+++ b/src/Tests/CustomDataTypesUnitTest.php
@@ -80,7 +80,7 @@ class CustomDataTypesUnitTest extends EntityUnitTestBase {
    */
   public function testCustomDataTypes() {
     $original_value = $this->entities[1]->get('name')->value;
-    $original_type = $this->index->getFields()['entity:entity_test/name']->getType();
+    $original_type = $this->index->getCachedFields()['entity:entity_test/name']->getType();
 
     $item = $this->index->loadItem('entity:entity_test/1:en');
     $item = Utility::createItemFromObject($this->index, $item, 'entity:entity_test/1:en');
@@ -95,7 +95,7 @@ class CustomDataTypesUnitTest extends EntityUnitTestBase {
     // Reset the fields on the item and change to the supported data type.
     $item->setFieldsExtracted(FALSE);
     $item->setFields(array());
-    $this->index->getFields()['entity:entity_test/name']->setType('search_api_test_data_type');
+    $this->index->getCachedFields()['entity:entity_test/name']->setType('search_api_test_data_type');
     $name_field = $item->getField('entity:entity_test/name');
 
     $processed_value = $name_field->getValues()[0];
@@ -107,7 +107,7 @@ class CustomDataTypesUnitTest extends EntityUnitTestBase {
     // Reset the fields on the item and change to the non-supported data type.
     $item->setFieldsExtracted(FALSE);
     $item->setFields(array());
-    $this->index->getFields()['entity:entity_test/name']->setType('search_api_unsupported_test_data_type');
+    $this->index->getCachedFields()['entity:entity_test/name']->setType('search_api_unsupported_test_data_type');
     $name_field = $item->getField('entity:entity_test/name');
 
     $processed_value = $name_field->getValues()[0];
@@ -119,7 +119,7 @@ class CustomDataTypesUnitTest extends EntityUnitTestBase {
     // Reset the fields on the item and change to the data altering data type.
     $item->setFieldsExtracted(FALSE);
     $item->setFields(array());
-    $this->index->getFields()['entity:entity_test/name']->setType('search_api_altering_test_data_type');
+    $this->index->getCachedFields()['entity:entity_test/name']->setType('search_api_altering_test_data_type');
     $name_field = $item->getField('entity:entity_test/name');
 
     $processed_value = $name_field->getValues()[0];
diff --git a/src/Tests/IntegrationTest.php b/src/Tests/IntegrationTest.php
index 4d71336..7b8888a 100644
--- a/src/Tests/IntegrationTest.php
+++ b/src/Tests/IntegrationTest.php
@@ -62,6 +62,7 @@ class IntegrationTest extends WebTestBase {
    * Tests various operations via the Search API's admin UI.
    */
   public function testFramework() {
+
     $this->drupalLogin($this->adminUser);
 
     // Test that the overview page exists and its permissions work.
@@ -450,8 +451,10 @@ class IntegrationTest extends WebTestBase {
 
     $edit = array('fields[entity:node/field__field_][indexed]' => 1);
     $this->drupalGet($this->getIndexPath('fields'));
+    $this->assertHtmlEscaped($field_name);
     $this->drupalPostForm(NULL, $edit, $this->t('Save changes'));
     $this->assertHtmlEscaped($field_name);
+    $this->assertFieldChecked('edit-fields-entitynodefield-field-indexed');
 
     $edit = array(
       'datasource_configs[entity:node][default]' => 1,
@@ -485,7 +488,7 @@ class IntegrationTest extends WebTestBase {
     $this->indexStorage->resetCache(array($this->indexId));
     /** @var $index \Drupal\search_api\IndexInterface */
     $index = $this->indexStorage->load($this->indexId);
-    $fields = $index->getFields(FALSE);
+    $fields = $index->getCachedFields(FALSE);
 
     $this->assertEqual($fields['entity:node/nid']->isIndexed(), $edit['fields[entity:node/nid][indexed]'], 'nid field is indexed.');
     $this->assertEqual($fields['entity:node/title']->isIndexed(), $edit['fields[entity:node/title][indexed]'], 'title field is indexed.');
@@ -532,7 +535,7 @@ class IntegrationTest extends WebTestBase {
     $this->indexStorage->resetCache(array($this->indexId));
     /** @var $index \Drupal\search_api\IndexInterface */
     $index = $this->indexStorage->load($this->indexId);
-    $fields = $index->getFields();
+    $fields = $index->getCachedFields();
     $this->assertTrue(!isset($fields['entity:node/body']), 'The body field has been removed from the index.');
   }
 
diff --git a/src/Tests/Processor/ProcessorTestBase.php b/src/Tests/Processor/ProcessorTestBase.php
index 57a9ed0..93ea110 100644
--- a/src/Tests/Processor/ProcessorTestBase.php
+++ b/src/Tests/Processor/ProcessorTestBase.php
@@ -92,7 +92,7 @@ abstract class ProcessorTestBase extends EntityUnitTestBase {
       'tracker' => 'default',
     ));
     $this->index->setServer($this->server);
-    $this->index->setOption('fields', array(
+    $this->index->setFields(array(
       'entity:comment/subject' => array(
         'type' => 'text',
       ),
diff --git a/tests/search_api_test_db/config/install/search_api.index.database_search_index.yml b/tests/search_api_test_db/config/install/search_api.index.database_search_index.yml
index d76f3d7..5bd2ee6 100644
--- a/tests/search_api_test_db/config/install/search_api.index.database_search_index.yml
+++ b/tests/search_api_test_db/config/install/search_api.index.database_search_index.yml
@@ -8,25 +8,25 @@ processors:
     weights:
       preprocess_index: -50
     settings: {  }
+fields:
+  'entity:entity_test/id':
+    type: integer
+  'entity:entity_test/name':
+    type: text
+    boost: 5.0
+  'entity:entity_test/body':
+    type: text
+  'entity:entity_test/type':
+    type: string
+  'entity:entity_test/keywords':
+    type: string
+  'entity:entity_test/category':
+    type: string
+  search_api_language:
+    type: string
 options:
   cron_limit: -1
   index_directly: false
-  fields:
-    'entity:entity_test/id':
-      type: integer
-    'entity:entity_test/name':
-      type: text
-      boost: 5.0
-    'entity:entity_test/body':
-      type: text
-    'entity:entity_test/type':
-      type: string
-    'entity:entity_test/keywords':
-      type: string
-    'entity:entity_test/category':
-      type: string
-    search_api_language:
-      type: string
 datasources:
   - 'entity:entity_test'
 datasource_configs: {  }
diff --git a/tests/search_api_test_hooks/search_api_test_hooks.module b/tests/search_api_test_hooks/search_api_test_hooks.module
index d400acd..4475cd1 100644
--- a/tests/search_api_test_hooks/search_api_test_hooks.module
+++ b/tests/search_api_test_hooks/search_api_test_hooks.module
@@ -85,7 +85,7 @@ function search_api_test_hooks_search_api_field_type_mapping_alter(array &$mappi
  */
 function search_api_test_hooks_search_api_query_andrew_hill_alter(\Drupal\search_api\Query\QueryInterface &$query) {
   // Exclude the node with ID 2 from the search results.
-  $fields = $query->getIndex()->getFields();
+  $fields = $query->getIndex()->getCachedFields();
   foreach ($query->getIndex()->getDatasources() as $datasource_id => $datasource) {
     if ($datasource->getEntityTypeId() == 'node') {
       $field = \Drupal\search_api\Utility::createCombinedId($datasource_id, 'nid');