I'm doing a rewrite[0] of OctoSQL[1], partly to make it push-based instead of pull-based, and for now it's been much simpler to work with, won't get into the detailed reasoning in this comment.

However, if somebody is interested, this is a great paper on how to architect a query compiler: https://www.cs.purdue.edu/homes/rompf/papers/tahboub-sigmod1...

I found it very enlightening and simple to implement. The paper also delves into details why the push-based architecture has more room for optimizations.

[0]:https://github.com/cube2222/octosql/tree/redesign

[1]:https://github.com/cube2222/octosql/