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Re: st: bug: non-unique merge

Subject   Re: st: bug: non-unique merge
Date   Wed, 05 Oct 2005 08:42:54 -0500

James Muller <> said:

> I have noticed a little problem with non-unique merging, when the sort
> option is used. Sort appears to set the 'unique master' option. I'll
> give an example:
> <cut>
> The error I receive is that "variable id does not uniquely identify
> observations in the master data". If re-run the above example except
> manually sort each dataset and do not set the sort option then it
> returns a warning rather than an error.
> The help on merge describes the 'unique' option as options as, if
> specified then uniqueness is a requirement but otherwise it is not. I
> quote:
> <cut>
> There is nothing said in the description of the sort option. And so
> the above example should produce the dataset:
> <cut>
> It isn't anything serious, I know, but it's not the stated behaviour
> for merge.

Look at the options table under the syntax diagram in -help
merge- (or in the manual for [D] merge).  At the bottom of that
table it says

    sort implies unique.

So it is not a bug.  But, it looks like we should state this
again down in the options section.  I will see about changing
merge.hlp (and eventually the manual) so that in the description
of the -sort- option down in the Options section it will also say

Ken Higbee
StataCorp     1-800-STATAPC

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