The $shardedDataDistribution aggregation stage is supposed to return 4 fields : numOrphanedDocs, numOwnedDocuments, ownedSizeBytes and orphanedSizeBytes.

When the stage is invoked on a bucket collection, it correctly reports the numOrphanedDocs but outputs null for all other fields. The bug arises because $shardedDataDistribution relies on the output of the $collStats aggregation stage that outputs a different set of fields for timeseries collections.

Those are the ways we currently compute the number of owned docs, owned size and orphaned size in the $shardedDataDistribution stage relying on storageStats.count and storageStats.avgObjSize. Purpose of this ticket is to change the stage to compute such metrics based on timeseries.bucketCount and timeseries.avgBucketSize when invoked on a bucket collection.