  Semistructured databases require tailor-made concurrency control mechanisms
since traditional solutions for the relational model have been shown to be
inadequate. Such mechanisms need to take full advantage of the hierarchical
structure of semistructured data, for instance allowing concurrent updates of
subtrees of, or even individual elements in, XML documents. We present an
approach for concurrency control which is document-independent in the sense
that two schedules of semistructured transactions are considered equivalent if
they are equivalent on all possible documents. We prove that it is decidable in
polynomial time whether two given schedules in this framework are equivalent.
This also solves the view serializability for semistructured schedules
polynomially in the size of the schedule and exponentially in the number of
transactions.
