040000 tree b2094a57b111f59ef02e047dc51e11320c9e9203	external-indexing
040000 tree 68f91b7da6b44878363bffe97534e40e917c0a49	index-join
040000 tree 46b963d6352154d17755970fb8b262ef79133594	index-leftouterjoin
040000 tree 4feb046be037bec858b189f7bbf207fca8838855	index-selection