you have to implement
these algorithms you are using optimistic concurrency control approach, i.e. all writes become visible only after commit.
It can be seen that the advantage of this approach: upon an abort of a transaction, no
rollback is necessary as none of the writes of the transactions will ever be visible.
An important requirement with MVTO algorithm is to collect the unwanted (garbage) ver-
sions. So, you have to implement the garbage collection procedure