Query indexed column with key filter‏

[Daning]

I found this code

        // Start and finish keys, *and* column relations (KEY>  foo AND KEY<  
bar and name1 = value1).
        if (select.isKeyRange()&&  (select.getKeyFinish() != null)&&  
(select.getColumnRelations().size()>  0))
            throw new InvalidRequestException("You cannot combine key range and 
by-column clauses in a SELECT");
in

http://svn.apache.org/repos/asf/cassandra/trunk/src/java/org/apache/cassandra/cql/QueryProcessor.java


This operation is exactly what I want - query by column then filter by 
key. I want to know why this query is not supported, and what's the good 
work around for it? At this moment my workaound is to create a column 
which is exactly same as key.

Thanks,

Daning