There are a lot of XML databases. A comprehensive list can be found on the web here But it seems that all Open Source native XML databases at the moment of writing MyX cannot hold large documents (i.e. 8MB) because they work with document's DOM tree, and DOM is very memory consuming.

Most popular Java Open Source native XML database are Xindice (part of well known and respected Apache Jakarta foundation), eXist and dbXML. But they at the moment of writing this text don't support large files. And I didn't found any alternative Open Source solution to store and query large XML data (files) in Java.

But, it seems that all native XML databases implement XML:DB API, see XML:Db API . Myx is implementation of XML:DB API (XML database repository layer) using MySQL. Querying is possible using Saxon (author at the moment . Myx is capable of storing and querying large documents.

Why Myx

It might be capable to store and query large files other Open Source implementation aren't.
It is simple implementation of XML:DB API, so you might use it as a help to add support to your project.
It is only implementation which put data into SQL BLOB so you might find it interesting to do speed comparison test with other databases.
Tell me your reasons