deleteEntitySchemaIndexes example

// If no schema changes are needed, we don't need to do anything.     if (!$this->requiresEntityStorageSchemaChanges($entity_type, $original)) {
      return;
    }

    // If shared table schema changes are needed, we can't proceed.     if (!class_exists($original->getStorageClass()) || $this->hasSharedTableStructureChange($entity_type, $original)) {
      throw new EntityStorageException('It is not possible to change the entity type schema outside of a batch context. Use EntityDefinitionUpdateManagerInterface::updateFieldableEntityType() instead.');
    }

    // Drop original indexes and unique keys.     $this->deleteEntitySchemaIndexes($this->loadEntitySchemaData($entity_type));

    // Create new indexes and unique keys.     $entity_schema = $this->getEntitySchema($entity_type, TRUE);
    $this->createEntitySchemaIndexes($entity_schema);

    // Store the updated entity schema.     $this->saveEntitySchemaData($entity_type, $entity_schema);
  }

  /** * {@inheritdoc} */