Give an example of an instance of the Transcript relation (with the attributes StudId, CrsCode, Semester, and Grade) and a hash function on the attribute sequence {StudId; Grade} that sends two identical tuples in StudId;Semester(Transcript) into different hash buckets.
What will be an ideal response?
Consider the following two tuples: <111111111; EE101; F1997; A> and <111111111,MAT123,F1997,Bi> Since these tuples have identical projections on the attributes StudId,Semester, they become one in the projected relation
StudId;Semester(Transcript)
Consider now the following hash function on StudId,Grade:
f (t) = (t:StudId + (t:Grade - 'A')) mod 1000
The first tuple will then be sent to the bucket 111111111 mod 1000 = 111 and the second to 111111112 mod 1000 = 112.
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