rename columnlist to output_columns
add test for multiway join using fakedb.
refactor catalog.
adopt bill’s suggestion: using system R’s heuristic
address danH’s comments, more proper behavior of num_tuples
refactor catalog
Sequence does not return tuple directly
Rename MyriaLDTreeAlbegra to full name.
test naryjoin merge condition.
use `all` and `any` to simplify code.