On the Internet, query processing capabilities of sources may be 
limited in diverse ways, and this makes answering even the 
simplest queries challenging.  In this paper, we present a 
scheme called GenCompact for generating capability sensitive 
plans for selection queries.  The generated query plans may 
be better than what existing query processing systems produce 
for three reasons: (1) the sources are guaranteed to support 
the query plans; (2) the plans take full advantage of the 
source capabilities; and (3) the plans may be more efficient 
since a larger space of plans is examined.  Even though 
GenCompact considers many plans, it is relatively efficient
because it uses effective data structures and pruning rules.
We study the optimality of the plans generated as well as the 
efficiency of the plan generation process.