Alternative correctness criteria for concurrent execution of transactions in multilevel secure databases
Sushil Jajodia, Vijayalakshmi Atluri · 2003
Two different areas related to the concurrency control in multilevel secure, multiversion databases are considered. First, the issue of correctness criteria that are weaker than one-copy serializability are explored. The requirements for a weaker correctness criterion are that it should preserve database consistency in some meaningful way, and moreover, it should be implementable in a way that does not require the scheduler to be trusted. Three different, increasingly stricter notions of serializability that can serve as substitutes for one-copy serializability are proposed. Second, a multiversion timestamping protocol is presented that has several very desirable properties: it is secure, produces multiversion histories that are equivalent to one-serial histories in which transactions are placed in a timestamp order, avoids livelocks, and can be implemented using single-level untrusted schedulers.>