Mysql index dimension

Question

I have the number of rows in row x, but all index metrics are much larger than x, how is this possible? If I understand correctly, index power is the number of unique rows of this index.

Answer 1

FROM SHOW INDEX :

Cardinality
Estimate the number of unique values ​​in the index. This is updated by running ANALYZE TABLE or myisamchk -a. The power value is calculated based on statistics stored as integers, so the value is not necessarily accurate even for small tables.

Answer 2

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