diff --git a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php
index 91ca92b..c62fc06 100644
--- a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php
+++ b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php
@@ -271,6 +271,13 @@ public function setEntityType(EntityTypeInterface $entity_type) {
   public function getTableMapping(array $storage_definitions = NULL) {
     $table_mapping = $this->tableMapping;
 
+    // If we are using our internal storage definitions, which is our main use
+    // case, we can statically cache the computed table mapping. If a new set
+    // of field storage definitions is passed,for instance when comparing old
+    // and new storage schema, we just compute the table mapping but skip any
+    // caching.
+    // @todo Clean-up this in https://www.drupal.org/node/2274017 so we can
+    //   easily instantiate a new table mapping whenever needed.
     if (!isset($this->tableMapping) || $storage_definitions) {
       $definitions = $storage_definitions ?: $this->entityManager->getFieldStorageDefinitions($this->entityTypeId);
       $base_field_definitions = $this->entityManager->getBaseFieldDefinitions($this->entityTypeId);
@@ -382,6 +389,8 @@ public function getTableMapping(array $storage_definitions = NULL) {
         }
       }
 
+      // Cache the computed table mapping only if we are using our internal
+      // storage definitions.
       if (!$storage_definitions) {
         $this->tableMapping = $table_mapping;
       }
diff --git a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php
index 168b1bd..37d2067 100644
--- a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php
+++ b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php
@@ -418,7 +418,7 @@ protected function getEntitySchema(ContentEntityTypeInterface $entity_type, $res
         }
         foreach ($table_mapping->getFieldNames($table_name) as $field_name) {
           if (!isset($storage_definitions[$field_name])) {
-            throw new FieldException(String::format('Fieled storage definition for "@field_name" could not be found.', array('@field_name' => $field_name)));
+            throw new FieldException(String::format('Field storage definition for "@field_name" could not be found.', array('@field_name' => $field_name)));
           }
           // Add the schema for base field definitions.
           elseif ($table_mapping->allowsSharedTableStorage($storage_definitions[$field_name])) {