Cost based optimization (#226)

[galipremsagar]

• Refactoring of the planner logic

• Extract out utility classes for easier development

• Strip the optimization into a non-cost based (using the same rules as
  before) and a volcano planner.

• For this, implement physical nodes (with a DaskRel) which are so far
  only a copy of the already present logical nodes (but with a different
  convention).

• Only exception: split the sort+limit into a sort and a limit

• Adjust the python implementations to follow the new conventions

• Fix a bug in the column name creation and in the window node. While doing this, improve the logging output

• Implement the missing sample node

• Calcite is now creating a new function: /int. Implement it

• Additional optimization rules (probably not needed)

• Expaning will lead to RexSubQueries, which are harder to handle and not implemented. So keep the default

• Documentation

• Allow the user to pass in row-count statistics on the tables, which are then used in the optimization

• List.of is a Java 11 feature -> replace with Arrays.asList to stay java-8 compatible

• Bring the coverage up again

• Run pre-commit hooks

• Remove formatted brackets causing explain failures

• apply changes from Jeremy

Co-authored-by: Charles Blackmon-Luca [email protected]
Co-authored-by: galipremsagar [email protected]

[charlesbluca]

Thanks @galipremsagar - just noting that the tests won't run until #15 is merged in. That being said, this should be safe to merge in as is