Complexity of Earliest Query Answering with Streaming Tree Automata

We investigate the complexity of earliest query answering for n-ary node selection queries defined by streaming tree automata (STAs). We elaborate an algorithm that selects query answers upon reception of the shortest relevant prefix of the input tree on the stream. In general, deciding if a prefix is sufficient for the selection of a n-tuple is DEXPTIME-complete (even for n = 0). For queries defined by deterministic STAs, this decision problem is in polynomial time combined complexity, as implemented in our earliest query answering algorithm. Keywords streaming, database theory, tree automata, XML, query languages

• Type: Conference
• Year: 2008
• Where: PLANX
• Authors: Olivier Gauwin, Anne-Cécile Caron, Joachim Niehren, Sophie Tison
• Keywords: Earliest Query, PLANX 2008, Programming Languages, Shortest Relevant Prefix, Tree Automata