Describe howthe two-phase commit protocol can be expanded to deal with a cohort site that uses a timestamp-ordered concurrency control.
What will be an ideal response?
The protocol described in the text assumes that cohorts use strict two-phase locking controls and hence that transactions are serialized in commit order. In order to achieve serialization in commit order, when a site using a time-stamp ordered concurrency control receives a prepare message for a transaction T, it checks to see whether T has a time-stamp later than all committed or prepared subtransactions. If so, it votes
ready; if not it votes aborting.
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Which operation does not take place in the following example?
int x = 21; double y = 6; double z = 14; y = x / z; x = 5.5 * y; a. Implicit conversion. b. Promotion. c. Explicit conversion. d. Truncation.
On average in a sequential search, how many comparisons would have to be made to find an element in the list in the accompanying figure?
A. 2 B. 5 C. 6 D. 8