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Re: st: Error 909: obs must be between 0 and NNN

From   [email protected] (William Gould, StataCorp LP)
To   [email protected]
Subject   Re: st: Error 909: obs must be between 0 and NNN
Date   Tue, 29 Jan 2008 09:28:07 -0600

Sergiy Radyakin <[email protected]> asks, 

> Another thing is the pointer size, that is needed to correctly
> estimate the data overhead. As 32-bit machines are being phased out by
> modern 64-bit number crunchers, the pointer size in Stata will also
> change from 4bytes to 8bytes? 

Yes.  The reason Sirgiy is asking the question is that Stata allocates a
pointer to each observation, and that pointer is 4 bytes on 32-bit computers
and 8 bytes on 64-bit computers.  Thus, however wide your dataset is, it's
memory footprint, per observation, is 4 or 8 bytes wider than that.

For instance, if you type -describe, detail- after using auto.dta, you will
find that its width is 43 bytes.  43 is what you would get if you summed the
individual lengths of the variables.  Thus, the width of the data when stored
in memory is 43 plus 4 or 8.

> Is pointer size or machine type reported somewhere?

After command -memory-, the size of a pointer is returned in r(size_ptr).
It is either 4 or 8.

-- Bill
[email protected]
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