diff -u b/core/config/schema/core.data_types.schema.yml b/core/config/schema/core.data_types.schema.yml
--- b/core/config/schema/core.data_types.schema.yml
+++ b/core/config/schema/core.data_types.schema.yml
@@ -445,9 +445,9 @@
     case_sensitive:
       type: boolean
       label: 'Case sensitive'
-    is_alphanumeric:
+    is_trivial:
       type: boolean
-      label: 'US ASCII characters only'
+      label: 'Contains US ASCII characters only'
 
 field.field_settings.string:
   type: mapping
diff -u b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/LanguageItem.php b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/LanguageItem.php
--- b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/LanguageItem.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/LanguageItem.php
@@ -44,7 +44,7 @@
   public static function propertyDefinitions(FieldStorageDefinitionInterface $field_definition) {
     $properties['value'] = DataDefinition::create('string')
       ->setLabel(t('Language code'))
-      ->setSetting('is_alphanumeric', TRUE)
+      ->setSetting('is_trivial', TRUE)
       ->setRequired(TRUE);
 
     $properties['language'] = DataReferenceDefinition::create('language')
@@ -76,6 +76,7 @@
         'value' => array(
           'type' => 'varchar',
           'length' => 12,
+          'is_alphanumeric' => TRUE,
         ),
       ),
     );
diff -u b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/StringItem.php b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/StringItem.php
--- b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/StringItem.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/StringItem.php
@@ -46,7 +46,7 @@
           'type' => 'varchar',
           'length' => (int) $field_definition->getSetting('max_length'),
           'binary' => $field_definition->getSetting('case_sensitive'),
-          'is_alphanumeric' => $field_definition->getSetting('is_alphanumeric'),
+          'is_alphanumeric' => $field_definition->getSetting('is_trivial'),
         ),
       ),
     );
diff -u b/core/modules/aggregator/src/Entity/Feed.php b/core/modules/aggregator/src/Entity/Feed.php
--- b/core/modules/aggregator/src/Entity/Feed.php
+++ b/core/modules/aggregator/src/Entity/Feed.php
@@ -226,7 +226,7 @@
 
     $fields['hash'] = BaseFieldDefinition::create('string')
       ->setLabel(t('Hash'))
-      ->setSetting('is_alphanumeric', TRUE)
+      ->setSetting('is_trivial', TRUE)
       ->setDescription(t('Calculated hash of the feed data, used for validating cache.'));
 
     $fields['etag'] = BaseFieldDefinition::create('string')
diff -u b/core/modules/aggregator/src/FeedInterface.php b/core/modules/aggregator/src/FeedInterface.php
--- b/core/modules/aggregator/src/FeedInterface.php
+++ b/core/modules/aggregator/src/FeedInterface.php
@@ -170,8 +170,8 @@
    * Sets the calculated hash of the feed data, used for validating cache.
    *
    * @param string $hash
-   *   A string containing the calculated hash of the feed. Must be base64
-   *   encoded so it contains US ASCII characters only.
+   *   A string containing the calculated hash of the feed. Must contain
+   *   US ASCII characters only.
    *
    * @return \Drupal\aggregator\FeedInterface
    *   The class instance that this method is called on.
diff -u b/core/modules/file/src/Entity/File.php b/core/modules/file/src/Entity/File.php
--- b/core/modules/file/src/Entity/File.php
+++ b/core/modules/file/src/Entity/File.php
@@ -254,7 +254,7 @@
 
     $fields['filemime'] = BaseFieldDefinition::create('string')
       ->setLabel(t('File MIME type'))
-      ->setSetting('is_alphanumeric', TRUE)
+      ->setSetting('is_trivial', TRUE)
       ->setDescription(t("The file's MIME type."));
 
     $fields['filesize'] = BaseFieldDefinition::create('integer')
diff -u b/core/modules/locale/locale.install b/core/modules/locale/locale.install
--- b/core/modules/locale/locale.install
+++ b/core/modules/locale/locale.install
@@ -188,6 +188,7 @@
         'type' => 'varchar',
         'length' => '255',
         'not null' => TRUE,
+        'is_alphanumeric' => TRUE,
         'default' => '',
         'description' => 'A unique short name to identify the project the file belongs to.',
       ),
@@ -195,6 +196,7 @@
         'type' => 'varchar',
         'length' => '12',
         'not null' => TRUE,
+        'is_alphanumeric' => TRUE,
         'default' => '',
         'description' => 'Language code of this translation. References {language}.langcode.',
       ),
diff -u b/core/modules/menu_link_content/src/Entity/MenuLinkContent.php b/core/modules/menu_link_content/src/Entity/MenuLinkContent.php
--- b/core/modules/menu_link_content/src/Entity/MenuLinkContent.php
+++ b/core/modules/menu_link_content/src/Entity/MenuLinkContent.php
@@ -250,7 +250,7 @@
       ->setLabel(t('Bundle'))
       ->setDescription(t('The content menu link bundle.'))
       ->setSetting('max_length', EntityTypeInterface::BUNDLE_MAX_LENGTH)
-      ->setSetting('is_alphanumeric', TRUE)
+      ->setSetting('is_trivial', TRUE)
       ->setReadOnly(TRUE);
 
     $fields['title'] = BaseFieldDefinition::create('string')
@@ -293,7 +293,7 @@
       ->setLabel(t('Menu name'))
       ->setDescription(t('The menu name. All links with the same menu name (such as "tools") are part of the same menu.'))
       ->setDefaultValue('tools')
-      ->setSetting('is_alphanumeric', TRUE);
+      ->setSetting('is_trivial', TRUE);
 
     $fields['link'] = BaseFieldDefinition::create('link')
       ->setLabel(t('Link'))
diff -u b/core/modules/node/node.install b/core/modules/node/node.install
--- b/core/modules/node/node.install
+++ b/core/modules/node/node.install
@@ -79,6 +79,7 @@
         'type' => 'varchar',
         'length' => 255,
         'not null' => TRUE,
+        'is_alphanumeric' => TRUE,
         'default' => '',
       ),
       'grant_view' => array(
diff -u b/core/modules/system/src/Tests/Database/SchemaTest.php b/core/modules/system/src/Tests/Database/SchemaTest.php
--- b/core/modules/system/src/Tests/Database/SchemaTest.php
+++ b/core/modules/system/src/Tests/Database/SchemaTest.php
@@ -68,7 +68,7 @@
     // Assert that the column comment has been set.
     $this->checkSchemaComment($table_specification['fields']['test_field']['description'], 'test_table', 'test_field');
 
-    // Make sure that varchard fields have the correct collation.
+    // Make sure that varchar fields have the correct collation.
     $columns = db_query('SHOW FULL COLUMNS FROM {test_table}');
     foreach ($columns as $column) {
       if ($column->Field == 'test_field_string') {
only in patch2:
unchanged:
--- a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php
+++ b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php
@@ -1603,6 +1603,7 @@ protected function getDedicatedTableSchema(FieldStorageDefinitionInterface $stor
         'bundle' => array(
           'type' => 'varchar',
           'length' => 128,
+          'is_alphanumeric' => TRUE,
           'not null' => TRUE,
           'default' => '',
           'description' => 'The field instance bundle to which this row belongs, used when deleting a field instance',
@@ -1619,6 +1620,7 @@ protected function getDedicatedTableSchema(FieldStorageDefinitionInterface $stor
         'langcode' => array(
           'type' => 'varchar',
           'length' => 32,
+          'is_alphanumeric' => TRUE,
           'not null' => TRUE,
           'default' => '',
           'description' => 'The language code for this data item.',
only in patch2:
unchanged:
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
@@ -137,6 +137,7 @@ public static function schema(FieldStorageDefinitionInterface $field_definition)
           // If the target entities act as bundles for another entity type,
           // their IDs should not exceed the maximum length for bundles.
           'length' => $target_type_info->getBundleOf() ? EntityTypeInterface::BUNDLE_MAX_LENGTH : 255,
+          'is_alphanumeric' => TRUE,
         ),
       );
     }
only in patch2:
unchanged:
--- a/core/modules/comment/src/Entity/Comment.php
+++ b/core/modules/comment/src/Entity/Comment.php
@@ -303,6 +303,7 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
     $fields['entity_type'] = BaseFieldDefinition::create('string')
       ->setLabel(t('Entity type'))
       ->setDescription(t('The entity type to which this comment is attached.'))
+      ->setSetting('is_trivial', TRUE)
       ->setSetting('max_length', EntityTypeInterface::ID_MAX_LENGTH);
 
     $fields['comment_type'] = BaseFieldDefinition::create('entity_reference')
@@ -313,6 +314,7 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
     $fields['field_name'] = BaseFieldDefinition::create('string')
       ->setLabel(t('Comment field name'))
       ->setDescription(t('The field name through which this comment was added.'))
+      ->setSetting('is_trivial', TRUE)
       ->setSetting('max_length', FieldStorageConfig::NAME_MAX_LENGTH);
 
     return $fields;
only in patch2:
unchanged:
--- a/core/modules/system/database.api.php
+++ b/core/modules/system/database.api.php
@@ -293,6 +293,9 @@
  *       'varchar' or 'text' fields to use case-sensitive binary collation.
  *       This has no effect on other database types for which case sensitivity
  *       is already the default behavior.
+ *     - 'is_alphanumeric': A boolean indicating that MySQL should use
+ *       ASCII character encoding for the field. This helps index usage be
+ *       more efficient, and should be used on machine name fields.
  *     All parameters apart from 'type' are optional except that type
  *     'numeric' columns must specify 'precision' and 'scale', and type
  *     'varchar' must specify the 'length' parameter.
only in patch2:
unchanged:
--- a/core/modules/user/user.install
+++ b/core/modules/user/user.install
@@ -23,6 +23,7 @@ function user_schema() {
         'description' => 'The name of the module declaring the variable.',
         'type' => 'varchar',
         'length' => DRUPAL_EXTENSION_NAME_MAX_LENGTH,
+        'is_alphanumeric' => TRUE,
         'not null' => TRUE,
         'default' => '',
       ),
@@ -31,6 +32,7 @@ function user_schema() {
         'type' => 'varchar',
         'length' => 128,
         'not null' => TRUE,
+        'is_alphanumeric' => TRUE,
         'default' => '',
       ),
       'value' => array(