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Unformatted text preview: The server provides two operations for its clients: (1) read(i) returns the value of ai; and (2) write(i; value) assigns “value” to ai. Consider the following interleaving of transactions T, U, and V: Time 1 2 3 4 5 6 7 8 9 10 T openTransaction y=read(k); U openTransaction x=read(k); write(i,55); write(j,66); commit; x=read(i); write(k,44); write(k,88); V openTransaction write(i,77); (a) (strict 2‐phase locking) Suppose the strict 2‐phase locking mechanism is used for concurrency control. Answer the following questions: (i) (ii) (iii) (iv) Does U have to wait to acquire the lock for x =read(k)? Does V have to wait to acquire the lock for write(k; 88)? Does T have to wa...
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This note was uploaded on 02/07/2013 for the course CS 425 taught by Professor Hu during the Spring '08 term at University of Illinois, Urbana Champaign.
- Spring '08