
Archives of the TeradataForumMessage Posted: Mon, 19 Jan 2004 @ 15:20:52 GMT
Craig, Mathematically these are two quite different things. Let me explain the difference using the simplest example. Table T had two columns, A and B, each of which can only take values 0 and 1. T has 100 rows, and 0 and 1 are distributed evenly in A and B, i.e., there exactly 50 0 and 50 1 in both A and B. Now, take all possible values of the pair (A,B): (0,0) I can have quite different tables of this kind: T1 has only (0,0) and (1,1), they occur 50 times each; T2 has all 4 combinations (0,0), (0,1), (1,0), (1,1), 25 times each. Obviously, T1 and T2 are quite different tables but their onedimensional projections are the same (50 0s and 50 1s in 100 rows). When you collect multicolumn statistics you should get more accurate (multidimensional) information (at least let's hope so!). Singlecolumn statistics describe projections only and they might be missing something important. Regards, Victor
 
 
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