2Q Replacement Policy

What
2Q replacement policy is an implementation of a buffer replacement policy inside of the buffer manager inside of DMBS

How
Maintain 2 queues (2Q policy). One queue, A1 queue, will hold pages that have only been referenced (pinned) only once. The second queue, A2 queue, will hold pages that have been referenced multiple times.

When it is necessary to select a page for replacement, priority goes to the A1 queue.