loadFieldSchemaData example

if ($storage_definition->hasCustomStorage()) {
      // The field has custom storage, so we don't know if a schema change is       // needed or not, but since per the initial checks earlier in this       // function, nothing about the definition changed that we manage, we       // return FALSE.       return FALSE;
    }

    $current_schema = $this->getSchemaFromStorageDefinition($storage_definition);
    $this->processFieldStorageSchema($current_schema);
    $installed_schema = $this->loadFieldSchemaData($original);
    $this->processFieldStorageSchema($installed_schema);

    return $current_schema != $installed_schema;
  }

  /** * Gets the schema data for the given field storage definition. * * @param \Drupal\Core\Field\FieldStorageDefinitionInterface $storage_definition * The field storage definition. The field that must not have custom * storage, i.e. the storage must take care of storing the field. * * @return array * The schema data. */