in Databases
524 views
2 votes
2 votes

It is not conflict serializable, So, why not option A) ??

in Databases
by
524 views

4 Comments

S4 is not possible because we cannot upgrade the lock because shared locked is already applied
0
0

Why you think it is allowed by some 2PL, 

We know If not CSS then Not 2PL.

Option a is wrong B/C S4 is wrong

1
1
only S3 is possible when you apply X(Z) it can not be acquired and leads to deadlock
0
0
Still not getting

where deadlock is possible?

2PL not allowed deadlock

Where deadlock possible?
0
0

1 Answer

0 votes
0 votes
$T_1 :\color{Red}{r_1(x)}...:\color{blue}{w_1(z)}$

$T_2 :\color{blue}{r_1(z)}...\color{Red}{w_1(x)}$

$\Rightarrow$   Same coloured operation on variables are conflicting therefore only serial schedule is possible so conflict serializability is not possible.
$\Rightarrow$   $\therefore$  Any non serial schedule will form deadlock because $2$pl maintain seriablizability and this schedule is not even possible to have interleaved operation.

1 comment

diagrmatically explain plz, specially the wait-for-graph
0
0