What benefit does strict two-phase locking provide? What disadvantages result?
Answer to relevant QuestionsWhat benefit does rigorous two-phase locking provide? How does it compare with other forms of two-phase locking?Consider the following graph-based locking protocol, which allows only exclusive lock modes, and which operates on data graphs that are in the form of a rooted directed acyclic graph.• A transaction can lock any vertex ...Although SIX mode is useful in multiple-granularity locking, an exclusive and intend-shared (XIS) mode is of no use. Why is it useless?Explain the phantom phenomenon. Why may this phenomenon lead to an incorrect concurrent execution despite the use of the two-phase locking protocol? Compare the shadow-paging recovery scheme with the log-based recovery schemes in terms of ease of implementation and overhead cost.
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