Mathis, ChristianHärder, TheoLehner, WolfgangMitschang, BernhardSchöning, HaraldSchwarz, Holger2019-01-172019-01-172011978-3-88579-274-1https://dl.gi.de/handle/20.500.12116/19602In the past, the development of a declarative, set-based interface to access data in a DBMS was a key factor for the success of database systems. For XML, the lingua franca for declarative data access is XQuery. This paper summarizes the XQuery processing concepts that have been developed in the XTC system (the XML Transaction Coordinator)-a native XML database management system. We step through all query processing stages: from parsing over query normalization, type checking, query simplification, query rewriting, and plan generation to the execution.enText/Conference Paper1617-5468