Fun project! I think Julia could be a great language for implementing things like using Bayesian statistical methods for estimating efficient query plans. :-)

Fun project! I think Julia could be a great language for implementing things like using Bayesian statistical methods for estimating efficient query plans. :-) Do you use the new iterators to implement the joins? If so, it seems reasonable that you could implement the join/filter as logical separate components but have the filtering happen in-line with the joins during iteration. Then you'd get the best of both worlds. It'd be interesting to see how well the Julia jit can inline that type of code! Also, if you're just getting into relational databases, definitely take some time to read up on the relational calculus, and relational algebra.