Post #4398816

@okennedy@discuss.systems here's a concrete example: O(g1, g2) G(g1, e1) G(g2, e2) E(e1, v) E(e2, v) FDs: G(g, e): g determines e uniquely E(e, v): e determines v uniquely so there are at most |O| results for this query. But, if my database is: E(e_1, v) ... E(e_n, v) G(g, e_1) ... G(g, e_n) and no O() facts at all there are no query results but a WCOJ can do n^2 > |O| work with variable order v, e1, e2, g1, g2: v <- {v : ∃e. E(e,v)} e1 <- {e : E(e,v) and ∃g. G(g,e)} e2 <- {e : E(e,v) and ∃g. G(g,e)} ...