apache/incubator-calcite — pull request #20 by vlsi (2014-11-28 21:18:00+00:00)
Title: Correlate update and implementation for enumerable convention

**DO NOT MERGE** **STILL WORK IN PROGRESS*

This facelifts Correlate relation and adds implementation for enumerables (i.e. nested loops, nested loops outer, nested loops semi, nested loops anti).
In current PR correlation/de-correlation should be intact (as much as it is possible). Special handling in planner/sql parser will be updated later.

A new planner config variable is added: forceDecorrelate=true(default)/false. By default planner still tries to de-correlate a lot, however for testing purposes de-correlation can be disabled. The setting might be removed if de-correlation is converted to cost-based-rule.

Note: this is a work in progress to track status in CI.