Adding index and cardinality

[greentea]

Hi,

When I add a new index to an existing table, I notice the cardinality starts with 0. Then I notice as I add more rows to a table, the table's cardinality starts to increase from 0.

Does that mean the newly index does not count the rows before index was added, and it only cares about the newly rows inserted?

If yes, how do I make the newly index care about all rows in the table?

Thanks,
John