>I have to import a discogs 21GB xml data file.
>
>Someone wrote a library that uses the API to read files larger than 2Gb.

IAC use a streaming parser, not a DOM based one for such huge amounts. In your shoes I'd look at Java / SAX based solution or split the large file into bettter digestable slurps of a few hundred MB with script file API if the XML can be easily parted.