Re: for-each-group group-by existing and non-existing

> but how does the group-by determine the correct groups? 

How does it work internally? I don't know, it's probably a pile of Java
that does something with hash tables, ask Michael:-)


> How does it know there is no value to do the grouping?

There always is a value. The grouping is not (directly) on the attribute
value (which may not be there) but on the string value of the
expression, which always (in this case) has a non empty value, the value
returned by current-grouping-key() and displayed in your condition=
attribute.

David


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