Optimistic vs. Pessimistic locking

Question

I understand the differences between optimistic and pessimistic locking. Now could someone explain to me when I would use either one in general?

And does the answer

Answer 1

In most cases, optimistic locking is more efficient and offers higher performance. When choosing between pessimistic and optimistic locking, consider the following:

• Pessimistic locking is useful if there are a lot of updates and relatively high chances of users trying to update data at the same time. For example, if each operation can update a large number of records at a time (the bank might add interest earnings to every account at the end of each month), and two applications are running such operations at the same time, they will have conflicts.

• Pessimistic locking is also more appropriate in applications that contain small tables that are frequently updated. In the case of these so-called hotspots, conflicts are so probable that optimistic locking wastes effort in rolling back conflicting transactions.

• Optimistic locking is useful if the possibility for conflicts is very low – there are many records but relatively few users, or very few updates and mostly read-type operations.