How to keep tracking on "People Who Viewed This Item Also Viewed"?

[oemript]

I would like to know on managing data, How to keep tracking on "People Who Viewed This Item Also Viewed"?
In order to generate a list of suggested items, should web page call database every time that user visit a product or category?

If yes, any approach to keep track on what items are viewed?
Does anyone have any suggestions?
Thanks in advance for any suggestions

 

Edited February 16, 2018 by oemript

[Earthshine]

Hitting the database every time the user visits the page seems a little heavy and could be problematic if there was millions of users or even thousands

Edited April 2, 2018 by Earthshine