public function registerDoctrineTypeMapping($dbType, $doctrineType)
    {
        if ($this->doctrineTypeMapping === null) {
            $this->initializeAllDoctrineTypeMappings();
        }

        if (! Types\Type::hasType($doctrineType)) {
            throw DBALException::typeNotFound($doctrineType);
        }

        $dbType                             = strtolower($dbType);
        $this->doctrineTypeMapping[$dbType] = $doctrineType;

        $doctrineType = Type::getType($doctrineType);

        if (! $doctrineType->requiresSQLCommentHint($this)) {
            return;
        }

        $this->markDoctrineTypeCommented($doctrineType);
    }