diff --git a/core/modules/migrate/migrate.install b/core/modules/migrate/migrate.install
index 582e5f7..fad5a2c 100644
--- a/core/modules/migrate/migrate.install
+++ b/core/modules/migrate/migrate.install
@@ -18,42 +18,3 @@ function migrate_update_8001() {
     $migration->save(TRUE);
   }
 }
-
-/**
- * Copy of Sql::getFieldSchema() for use by update hooks.
- *
- * @param array $id_definition
- *   The definition of the field having the structure as the items returned by
- *   MigrateSourceInterface or MigrateDestinationInterface::getIds().
- *
- * @return array
- *   The database schema definition.
- *
- * @see \Drupal\migrate\Plugin\migrate\id_map\Sql::getFieldSchema()
- */
-function _migrate_get_field_schema(array $id_definition) {
-  $type_parts = explode('.', $id_definition['type']);
-  if (count($type_parts) == 1) {
-    $type_parts[] = 'value';
-  }
-  unset($id_definition['type']);
-
-  // Get the field storage definition.
-  $definition = BaseFieldDefinition::create($type_parts[0]);
-
-  // Get a list of setting keys belonging strictly to the field definition.
-  $default_field_settings = $definition->getSettings();
-  // Separate field definition settings from custom settings. Custom settings
-  // are settings passed in $id_definition that are not part of field storage
-  // definition settings.
-  $field_settings = array_intersect_key($id_definition, $default_field_settings);
-  $custom_settings = array_diff_key($id_definition, $default_field_settings);
-
-  // Resolve schema from field storage definition settings.
-  $schema = $definition
-    ->setSettings($field_settings)
-    ->getColumns()[$type_parts[1]];
-
-  // Merge back custom settings.
-  return $schema + $custom_settings;
-}