Let $r_i(z)$ and $w_i(z)$ denote read and write operations respectively on…

GATE · 2021 · CS · Set 1 · Computer Science & IT

Let $r_i(z)$ and $w_i(z)$ denote read and write operations respectively on a data item $z$ by a transaction $T_i$ . Consider the following two schedules.

$S_1: r_1(x)r_1(y)r_2(x)r_2(y)w_2(y)w_1(x)$

$S_2: r_1(x)r_2(x)r_2(y)w_2(y)r_1(y)w_1(x)$

Which one of the following options is correct?

A.
$S_1$ is conflict serializable, and $S_2$ is not conflict serializable.
B.
$S_1$ is not conflict serializable, and $S_2$ is conflict serializable
C.
Both $S_1$ and $S_2$ are conflict serializable
D.
Neither $S_1$ nor $S_2$ is conflict serializable

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Let \(r_i(z)\) and \(w_i(z)\) denote read and write operations respectively on…