Dbms recoverablity

Question

Consider the following schedule

R1(a) W1(a) R2(a) commit2 W1(a) commit1

Is this schedule recoverable.I feel it is recoverable even though there is a dirty read

Comments

what do you mean by not vice-versa? even schedule which you mentioned it's also not recoverable.

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In my example, T1 is getting committed first so it's recoverable..

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ohh sorry i haven't checked the commit part i thought you just modified the write operation.... :)

Answer 1

RECOVERABLE SCHEDULE$:-$ A recoverable schedule is one where, for each pair of Transaction $T_{i}$ and $T_{j}$ such that if $T_{j}$ reads data item previously written by $ T_{i},$ then the commit operation of $T_{i}$ appears before the commit operation $T_{j}.$

$T_{1}$	$T_{2}$
R(a)
W(a)
	R(a)
	Commit
Commit

So this schedule is not recoverable.