IndexManager::saveOldFullText

protected function saveOldFullText(BaseObject $object)
{
	$textBuilder = $this->getTextBuilder($object);
	if (!ModuleManager::isModuleInstalled('bitrix24') && ($object instanceof File))
	{
		$content = $this->getFileContent($object);
		$maxIndexSize = Configuration::getMaxIndexSize();
		if ($maxIndexSize > 0)
		{
			//yes, we know that substr may kills some last characters
			$content = TextBinaryString::getSubstring($content, 0, $maxIndexSize);
		}

		$textBuilder->addText($content);
	}

	ObjectSaveIndexTable::update($object->getId(), array(
		'SEARCH_INDEX' => $textBuilder->getSearchValue(),
	));
}