setFieldStorageDefinitions example

->orderBy($identifier_field, 'ASC')
      ->range(0, $step_size)
      ->execute()
      ->fetchCol();

    /** @var \Drupal\Core\Entity\ContentEntityInterface[] $entities */
    $entities = $load_revisions ? $this->storage->loadMultipleRevisions($entity_identifiers) : $this->storage->loadMultiple($entity_identifiers);

    /** @var \Drupal\Core\Entity\Sql\SqlContentEntityStorage $temporary_storage */
    $temporary_storage = $this->entityTypeManager->createHandlerInstance($entity_type->getStorageClass(), $entity_type);
    $temporary_storage->setEntityType($entity_type);
    $temporary_storage->setFieldStorageDefinitions($field_storage_definitions);
    $temporary_storage->setTableMapping($sandbox['temporary_table_mapping']);

    foreach ($entities as $identifier => $entity) {
      try {
        if (!$original->isRevisionable() && $entity_type->isRevisionable()) {
          // Set the revision ID to be same as the entity ID.           $entity->set($revision_id_key, $entity->id());

          // We had no revisions so far, so the existing data belongs to the           // default revision now.           $entity->set($revision_default_key, TRUE);
        }

    $temporary_table_names = array_combine(
      $this->getTableNames($entity_type, $field_storage_definitions, $sandbox['new_table_mapping']),
      $this->getTableNames($entity_type, $field_storage_definitions, $sandbox['temporary_table_mapping'])
    );
    $this->entityType = $entity_type;
    $this->fieldStorageDefinitions = $field_storage_definitions;

    // Update the storage's entity type and field storage definitions because     // ::getEntitySchema() and ::getSharedTableFieldSchema() overrides are     // retrieving table names from these definitions.     $this->storage->setEntityType($entity_type);
    $this->storage->setFieldStorageDefinitions($field_storage_definitions);
    $this->storage->setTableMapping($sandbox['new_table_mapping']);

    $schema = $this->getEntitySchema($entity_type, TRUE);
    $sandbox['new_entity_schema'] = $schema;

    // Filter out tables which are not part of the table mapping.     $schema = array_intersect_key($schema, $temporary_table_names);

    // Create entity tables.     foreach ($schema as $table_name => $table_schema) {
      $this->database->schema()->createTable($temporary_table_names[$table_name], $table_schema);
    }