is Datastore needed for PMT performance monitoring tool

Want to install PMT - but when checking the install instructions there is reference to Datastore (which requires additional resources) and ElasticSearchh (which Datastore uses).  What is this and is it needed for PMT to work?

When I read up on PMT on the web (the various overviews) no mention is made of Datastore.

The page I referenced is Performance Monitoring Toolset deployment guide (adobe.com)

This impacts the size of VM I need to request or share with other apps.

if there is a web page that explains this, that may be sufficeient (cannot seem to find this).