Zend FR

function sanitize($input) 
{
    return utf8_decode( $input ) ;
    //return htmlentities( $input );
}

$index = new Zend_Search_Lucene(PATH_VAR . 'lucene/siteIndex', true);

//get all indexable contents id DB
$searchableContents = SiteTree::fetchSearchableSiteTreeEntries();
$counter = 0;

//parsing results of query
foreach ($searchableContents as $content) 
{ 

    if ($counter == 50)
    {
        $index->commit();
        $index = new Zend_Search_Lucene(PATH_VAR . 'lucene/siteIndex', true);
        $counter = 0;
    }
    if ( Lang::getLocaleById( $content->languageId ) != 'ar' ) 
    {
        $doc = new Zend_Search_Lucene_Document();       
        $doc->addField(Zend_Search_Lucene_Field::Text('title', sanitize($content->htmlTitle)));
        $doc->addField(Zend_Search_Lucene_Field::Text('intro', sanitize($content->htmlIntro)));
        $doc->addField(Zend_Search_Lucene_Field::Text('tags', sanitize($content->tags)));
        $doc->addField(Zend_Search_Lucene_Field::Text('language', Lang::getLocaleById( $content->languageId )));
        $doc->addField(Zend_Search_Lucene_Field::Text('keywords', sanitize($content->metaKey)));
        $doc->addField(Zend_Search_Lucene_Field::UnIndexed('siteTreeId',$content->id));
        $doc->addField(Zend_Search_Lucene_Field::Unstored('content', sanitize($content->htmlContent)));
    }
    $counter ++;
}
$index->commit();
$index->optimize();