We should not use the storageSize as size of the mongo db collection

Please find the following clarification.

Clarification 1.

·         size refers for logical allocation (this is seen by database engine)

·         storageSize refers for physical file space allocation

As WT (WiredTiger) is used, with enabled data compression, then physical allocation is smaller because of compression

Clarification 2.

We can calculate the size of the collection like the

Collection size  = avgObjSize*count

                         =  121 * 81871366 = 9906435286 bytes  (9.906435286 GB).

So, final word is that I think we should not use the storageSize as size of the collection.