Q$\mathrm{.}2$Set. $($B$)$

i$)$Consider a variant of the tree protocol called the forest protocol. The database is organized as a forest of rooted trees. Each transaction Ti must follow the following rules:

The first lock in each tree may be on any data item.

The second, and all subsequent, locks in a treemay be requested only if the parent of the requested node is currently locked.

Data items may be unlocked at any time.

A data item may not be relocked by $Ti$ after it has been unlocked by $Ti.$

Show that the forest protocol does not ensure serializability. $(6$ marks$)$

ii$)$

Consider the following two transactions:a$.$ Add lock and unlock instructions to transactions T $31$ and T $32,$ so that they observe the twophase locking protocol.$(2$ marks$)$b$.$ Can the execution of these transactions result in a deadlock? $(2$ marks$)$