You shouldn't use the Document Object Model on large XML files, it is intended for human readable documents, not big datasets!
If you want fast access you should use XMLReader or SimpleXML.
XMLReader is ideal for parsing whole documents, and SimpleXML has a nice XPath function for retreiving data quickly.
For XMLReader you can use the following code:
<?php
// Parsing a large document with XMLReader with Expand - DOM/DOMXpath
$reader = new XMLReader();
$reader->open("tooBig.xml");
while ($reader->read()) {
switch ($reader->nodeType) {
case (XMLREADER::ELEMENT):
if ($reader->localName == "game") {
$node = $reader->expand();
$dom = new DomDocument();
$n = $dom->importNode($node,true);
$dom->appendChild($n);
$xp = new DomXpath($dom);
$res = $xp->query("/game/title"); // this is an example
echo $res->item(0)->nodeValue;
}
}
}
?>
The above will output all game titles (assuming you have /game/title
XML structure).
For SimpleXML you can use:
$xml = file_get_contents($url);
$sxml = new SimpleXML($xml);
$games = $sxml->xpath('/game'); // returns an array of SXML nodes
foreach ($games as $game)
{
print $game->nodeValue;
}