单选题Consider the following: Which statement best describes the meaning of the value for the key_len column?（）A It shows the total size of the index rowB It shows how many columns in the index are examinedC It shows the number of characters indexed in the keyD It shows how many bytes will be used from each index row
单选题
Consider the following: Which statement best describes the meaning of the value for the key_len column?（）
A
It shows the total size of the index row
B
It shows how many columns in the index are examined
C
It shows the number of characters indexed in the key
D
It shows how many bytes will be used from each index row
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