ContentModerationStateStorageSchema.php

<?php

namespace Drupal\content_moderation;

use Drupal\Core\Entity\ContentEntityTypeInterface;
use Drupal\Core\Entity\Sql\SqlContentEntityStorageSchema;

/**
 * Defines the content moderation state schema handler.
 */
class ContentModerationStateStorageSchema extends SqlContentEntityStorageSchema {
    
    /**
     * {@inheritdoc}
     */
    protected function getEntitySchema(ContentEntityTypeInterface $entity_type, $reset = FALSE) {
        $schema = parent::getEntitySchema($entity_type, $reset);
        // Creates unique keys to guarantee the integrity of the entity and to make
        // the lookup in ModerationStateFieldItemList::getModerationState() fast.
        $unique_keys = [
            'content_entity_type_id',
            'content_entity_id',
            'content_entity_revision_id',
            'workflow',
            'langcode',
        ];
        if ($data_table = $this->storage
            ->getDataTable()) {
            $schema[$data_table]['unique keys'] += [
                'content_moderation_state__lookup' => $unique_keys,
            ];
        }
        if ($revision_data_table = $this->storage
            ->getRevisionDataTable()) {
            $schema[$revision_data_table]['unique keys'] += [
                'content_moderation_state__lookup' => $unique_keys,
            ];
        }
        return $schema;
    }

}