I have x row count, but all index cardinarlities are much greater than x, how is this possible? If I understand correctly, index cardinality is the number of unique rows of that index.
+1
A:
From SHOW INDEX:
Cardinality
An estimate of the number of unique values in the index. This is updated by running ANALYZE TABLE or myisamchk -a. Cardinality is counted based on statistics stored as integers, so the value is not necessarily exact even for small tables.
a1ex07
2010-07-26 18:18:01