diff -u b/core/modules/field_sql_storage/field_sql_storage.install b/core/modules/field_sql_storage/field_sql_storage.install
--- b/core/modules/field_sql_storage/field_sql_storage.install
+++ b/core/modules/field_sql_storage/field_sql_storage.install
@@ -12,16 +12,11 @@
   $schema = array();
 
   // Dynamic (data) tables.
-  // It's not safe to call field_read_fields() during maintenance mode.
-  // It's also not safe to call entity_load_multiple() during
-  // hook_schema() invocations.
-  if (!defined('MAINTENANCE_MODE')) {
-    $field_names = config_get_storage_names_with_prefix('field.field');
-    foreach ($field_names as $name) {
-      $field = config($name)->get();
-      if ($field['storage']['type'] == 'field_sql_storage') {
-        $schema += _field_sql_storage_schema($field);
-      }
+  $fields = field_read_fields(array(), array('include_deleted' => TRUE, 'include_inactive' => TRUE));
+  drupal_load('module', 'field_sql_storage');
+  foreach ($fields as $field) {
+    if ($field['storage']['type'] == 'field_sql_storage') {
+      $schema += _field_sql_storage_schema($field);
     }
   }