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Large Data Sets - It is worth the effort to be efficient?

How large is the data set created by this data step?

data bigone;
	drop i j k;
	array XX {*} X1-X100;
	do i=1 to 100;
		do j=1 to 100;
			do k=1 to dim(XX);
				XX(k)=k + 1000*j;

The SAS log says 10,000 observations and 100 variables. But how much space is needed to store the data set?

Let's see. Each numeric variable needs 8 bytes for each observation.
So, 8*100*10,000 = 8,000,000 bytes, or 7.63 megabytes. (1 meg = 1,048,576 bytes)
Some additional space is needed for the data descriptors, etc.
In all, this data set takes 8,209,408 bytes (7.83 meg).

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