Add support for the (relative) complement set operator "unless"

[grobie]

Prometheus currently supports intersection (and) and union (or). A relative complement operator would be great. Solr uses not as keyword, but @brian-brazil made a good suggestion to go with unless instead.

Example to return all bar_metric timeseries for instances not tagged with role foo.

bar_metric unless on(instance) roles{role="foo"}

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.