[Description] Average number of bytes per value for all of the key columns in the statistics object. [Column name] 
Average Key Length
N a m e
U p d a t e d
R o w s
R o w s S a m p l e d
S t e p s
D e n s i t y
A v e r a g e K e y L e n g t h
S t r i n g I n d e x
F i l t e r E x p r e s s i o n
U n f i l t e r e d R o w s