Hello @ken.chen
thanks for you reply. I am all aware of this. The initial question was how to find out which sizes does my working set for recent processed documents needs. If I give a mongod 64 GB it will use it also 128 GB and so on. The initial question could be rephrased as: how to measure the minimal size needed for recent documents in cache, So this is not like in the design phase where we estimate document sizes, connections and try to get a feeling, this is about to measure in a running system. Unfortunately this answer is not mentioned in any of the links. Did I missed this part or do we just have not such a metric?
Regards,
Michael