Методы работы с «тяжёлыми» XML

$xml = simplexml_load_file("price.xml");
echo "<table border='1'>\n";

foreach ($xml->xpath('/DocumentElement/price') as $producs) { ?> 
    <tr>
        <td><?php echo $producs->name; ?></td>
        <td><?php echo $producs->company; ?></td>
        <td><?php echo $producs->city; ?></td>
        <td><?php echo $producs->amount ?></td>
    </tr> 
<?
}
echo "</table>\n";

$doc = new DOMDocument();
$doc->load( 'books.xml' );
 
$books = $doc->getElementsByTagName( "book" );
foreach( $books as $book )
{
$authors = $book->getElementsByTagName( "author" );
$author = $authors->item(0)->nodeValue;
 
$publishers = $book->getElementsByTagName( "publisher" );
$publisher = $publishers->item(0)->nodeValue;
 
$titles = $book->getElementsByTagName( "title" );
$title = $titles->item(0)->nodeValue;
 
echo "$title - $author - $publisher\n";

class Simple_Parser 
{
    var $parser;
    var $error_code;
    var $error_string;
    var $current_line;
    var $current_column;
    var $data = array();
    var $datas = array();
    
    function parse($data)
    {
        $this->parser = xml_parser_create('UTF-8');
        xml_set_object($this->parser, $this);
        xml_parser_set_option($this->parser, XML_OPTION_SKIP_WHITE, 1);
        xml_set_element_handler($this->parser, 'tag_open', 'tag_close');
        xml_set_character_data_handler($this->parser, 'cdata');
        if (!xml_parse($this->parser, $data))
        {
            $this->data = array();
            $this->error_code = xml_get_error_code($this->parser);
            $this->error_string = xml_error_string($this->error_code);
            $this->current_line = xml_get_current_line_number($this->parser);
            $this->current_column = xml_get_current_column_number($this->parser);
        }
        else
        {
            $this->data = $this->data['child'];
        }
        xml_parser_free($this->parser);
    }

    function tag_open($parser, $tag, $attribs)
    {
        $this->data['child'][$tag][] = array('data' => '', 'attribs' => $attribs, 'child' => array());
        $this->datas[] =& $this->data;
        $this->data =& $this->data['child'][$tag][count($this->data['child'][$tag])-1];
    }

    function cdata($parser, $cdata)
    {
        $this->data['data'] .= $cdata;
    }

    function tag_close($parser, $tag)
    {
        $this->data =& $this->datas[count($this->datas)-1];
        array_pop($this->datas);
    }
}

$xml_parser = new Simple_Parser;
$xml_parser->parse('<foo><bar>test</bar></foo>');

<?php
<?php
Class StoreXMLReader
{
	
	private $reader;
	private $tag;
	
	// if $ignoreDepth == 1 then will parse just first level, else parse 2th level too
	
	private function parseBlock($name, $ignoreDepth = 1) {
		if ($this->reader->name == $name && $this->reader->nodeType == XMLReader::ELEMENT) {
			$result = array();
			while (!($this->reader->name == $name && $this->reader->nodeType == XMLReader::END_ELEMENT)) {
				//echo $this->reader->name. ' - '.$this->reader->nodeType." - ".$this->reader->depth."\n";
				switch ($this->reader->nodeType) {
					case 1:
						if ($this->reader->depth > 3 && !$ignoreDepth) {
							$result[$nodeName] = (isset($result[$nodeName]) ? $result[$nodeName] : array());
							while (!($this->reader->name == $nodeName && $this->reader->nodeType == XMLReader::END_ELEMENT)) {
								$resultSubBlock = $this->parseBlock($this->reader->name, 1);
								
								if (!empty($resultSubBlock))
									$result[$nodeName][] = $resultSubBlock;
								
								unset($resultSubBlock);
								$this->reader->read();
							}
						}
						$nodeName = $this->reader->name;
						if ($this->reader->hasAttributes) {
							$attributeCount = $this->reader->attributeCount;
							
							for ($i = 0; $i < $attributeCount; $i++) {
								$this->reader->moveToAttributeNo($i);
								$result['attr'][$this->reader->name] = $this->reader->value;
							}
							$this->reader->moveToElement();
						}
						break;
					
					case 3:
					case 4:
						$result[$nodeName] = $this->reader->value;
						$this->reader->read();
						break;
				}
				
				$this->reader->read();
			}
			return $result;
		}
	}

	public function parse($filename) {
		
		if (!$filename) return array();
		
		$this->reader = new XMLReader();
		$this->reader->open($filename);
		
		// begin read XML
		while ($this->reader->read()) {
			
			if ($this->reader->name == 'store_categories') {
			// while not found end tag read blocks
			while (!($this->reader->name == 'store_categories' && $this->reader->nodeType == XMLReader::END_ELEMENT)) {
				$store_category = $this->parseBlock('store_category');
				
				/*
					Do some code
				*/
				
				$this->reader->read();
			}
			
			$this->reader->read();
		}
			
		} // while
	} // func
}

$xmlr = new StoreXMLReader();
$r = $xmlr->parse('example.xml');

<?php
$xmlWriter = new XMLWriter();
$xmlWriter->openMemory();
$xmlWriter->startDocument('1.0', 'UTF-8');
$xmlWriter->startElement('shop');
for ($i=0; $i<=1000000; ++$i) {
    $productId = uniqid();

    $xmlWriter->startElement('product');
    $xmlWriter->writeElement('id', $productId);
    $xmlWriter->writeElement('name', 'Some product name. ID:' . $productId);
    $xmlWriter->endElement();
    // Flush XML in memory to file every 1000 iterations
    if (0 == $i%1000) {
        file_put_contents('example.xml', $xmlWriter->flush(true), FILE_APPEND);
    }
}
$xmlWriter->endElement();
// Final flush to make sure we haven't missed anything
file_put_contents('example.xml', $xmlWriter->flush(true), FILE_APPEND);