Github user cshannon commented on the issue:
https://github.com/apache/activemq-artemis/pull/1853
@clebertsuconic - I don't think we need to re-calculate anything if the
values are missing for paging. The point of this metric isn't to give the
user information on storage consumption as that data already exists. They can
find out how many page files are being used and disk usage already, etc.
The point of these metrics is to know exactly how much data on a queue is
left to consume. So there might be a 5 megabyte page file but only 2 messages
left to consume and the rest of the file is just waiting to be GC'd. This
metric only includes the 2 messages to be consumed and not the rest of the file.
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