The Simplest XML Storage Manager Ever

After more than four years of incubation within the W3C, XQuery 1.0 is close to completion. Even before its official release, development of numerous XQuery implementations is underway. However, those implementations have either focused on completeness or performance at the expense of the other. In this paper, we report on our experience building Jungle, a secondary storage manager for Galax. We designed Jungle to be the “simplest XML storage manager ever” that supports the complete XQuery 1.0 language, and we show it can scale to documents up to several hundred megabytes. Interestingly, the process of developing Jungle lead us to revisit several key features of currently proposed XML indexes. As a result, we propose alternative indices that provide more efficient support for the child axis and for XML serialization, two critical operations on the XQuery data model. Jungle is fully operational and now being deployed in production applications.