If an application scans by index, then serverStatus().indexCounters.btree.accesses shows the counts and activity against the index. However, if your application is performing scans not using an index (perhaps sub-optimally) there is no metric that shows anything. If a metric was exposed then it would be possible to spot poor plans/scans as well as do ratios of scans vs index accesses. Just a typical pattern for DBA's to see what the DB is doing at any given time. Perhaps the metric could be named: serverStatus().collections.scans. This is also good for an application where scans are needed (like the reads are most of the table) to show the DB activity during these periods. It's also a good measure of overall workload of the DB (scans/sec) and helps to differentiate different I/O patterns/performance. For instance how it changes when faults > 0, and also how it changes platform to platform (aka: I can scan more blocks with platform X).