// Constraints
	CreateConstraint(dst interface{}, name string) error
	DropConstraint(dst interface{}, name string) error
	HasConstraint(dst interface{}, name string) bool

	// Indexes
	CreateIndex(dst interface{}, name string) error
	DropIndex(dst interface{}, name string) error
	HasIndex(dst interface{}, name string) bool
	RenameIndex(dst interface{}, oldName, newName string) error

    }

    private void ensureIndexExists(final SearchEngineClient client, final String indexName) {
        if (!indexChecked) {
            if (!client.existsIndex(indexName)) {
                client.createIndex(NOTIFICATION_QUEUE_INDEX, indexName);
            }
            indexChecked = true;
        }
    }