Query cost

Let
r,s be two relations
rn – number of tuples of r
sn – number of tuples of s
rb – number of blocks of r
sb – number of blocks of s
R – attributes of r
S – attributes of s

Compute abstract r÷s I/O cost (forget CPU,comunications, buffers)

Any ideas?

Divison is not a primitive operation; It is implemented using a equivalent RA expression ΠR−S((ΠR−S(r)×s)−ΠR−S,S(r))

Rgds,
José Received on Fri Nov 08 2013 - 16:33:02 CET