Cardinality vs. distinct values
Dear all,
Can somebody explain to me the difference between cardinality and distinct(unique) values.
The reason I ask this is after I run an 'analyze table orders;' the 'show indexes from orders;' gives me a cardinality of 18 on my index created on the column order_id. But, when I run a 'select count(distinct order_id) from orders;' I receive a count of 47 distinct values.
I find this odd as I thought cardinality was indeed the count of unique values of a column.
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Cardinality vs. distinct values
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October 09, 2012 06:56AM
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October 31, 2012 03:07AM
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