Querying large XML file (600mb+) in PHP or JavaScript?

I have a large XML file (600mb+) and am developing a PHP application which needs to query this file.

My initial approach was to extract all the data from the file and insert it into a MySQL database - then query it that way. The only issue with this was that it was still slow, plus the XML data gets updated regularly - meaning I need to download, parse and insert data from the XML file into the database everytime the XML file is updated.

Is it actually possible to query a 600mb file? (for example, searching for records where TITLE="something here"?) Is it possible to get it to do this in a reasonable amount of t开发者_运维知识库ime?

Ideally would like to do this in PHP, though I could also use JavaScript too.

Any help and suggestions appreciated :)

Constructing an XML DOM for a 600+ Mb document is definitely a way to fail. What you need is SAX-based API. SAX, though, does not usually allow XPath to be used, but you can emulate it with imperative code.

As for the file being updated, is it possible to retrieve only differences anyhow? That would massively speed up subsequent processing.