In a workflow we built recently, we needed to know the combined size of all LUNs in a given volume. The SQL to calculate that number is fairly straightforward:
SELECT volume.name,SUM (lun.size_mb) FROM cm_storage.volume JOIN cm_storage.lun ON lun.volume_id = volume.id GROUP BY lun.volume_id
However, how can we return this information. And why would this even be a big deal ?
To answer this question in detail, you should first understand how WFA filters work.