That button is only active when the configuration of your view (ie the list of baselines listed by your config spec) isn't the same than the configuration of your stream.
The fact that is also update the view is only a side-effect of your view being a snapshot one.
For a snapshot view (ie a view on your disk):
- updating only the view will update the content based only on the config spec of said view (unchanged)
- synchronizing the view with the stream will trigger an update which will be based on the updated config spec of the view (ie the config spec of the view rewritten automaticaly for you, after reading the configuration of the associated Stream)
The fact that it updates your "integration view" is just because your view happens to be associated with the Integration Stream.
But as my previous answer on "Integration stream vs integration view in ClearCase" shows, there can be many other views (associated to many other sub-streams, also called "Development Streams").
Note: the cleartool command actually behind that button is:
cleartool -tag view setcs -stream.
If you execute it at the root directory of a snapshot view:
cleartool setcs -stream
It will trigger the update (after updating the config spec)
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