Incremental Evaluation of a Monotone XPath Fragment
by Hidetaka Matsumura, Keishi Tajima
This paper shows a scheme for incremental evaluation of XPath queries.
Here, we focus on a monotone fragment of XPath, i.e., when a data is
deleted from (or inserted to) the database, only deletion (insertion,
resp.) may occur to query answers. For efficiently processing
deletions, we store information on partial matchings, i.e., which
elements were participating in matchings for which query answers, and
also store counters showing how many matchings each query answer had.
We use the information on the partial matchings also for skipping a
part of computation upon data insertion. We investigate properties of
the XPath fragment in order to keep the amount of information we store
as small as possible.