According to the Merriam-Webster Dictionary, cardinality is defined as follows:
“Cardinality.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/cardinality.
So, for example, if you have a Python list of x = [1,2,3], its cardinality would be three. The cardinality of the set represented by the shard key represents the maximum number of shards possible. As an example, if your shard key is a country field containing ISO 3 country codes, the cardinality of this set would be the number of ISO 3 country codes (https://unstats.un.org/unsd/tradekb/Knowledgebase/Country-Code). This number at the time of writing, and thus the maximum number of chunks that could be created, is 246.
If, on the other hand, the shard key chosen is the seasons field, the cardinality would be 4 as there are four seasons. This means the maximum number...
