Github user amansinha100 commented on a diff in the pull request:
https://github.com/apache/drill/pull/705#discussion_r94437725
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/planner/logical/DrillMergeProjectRule.java
---
@@ -48,6 +50,12 @@ public boolean matches(RelOptRuleCall call) {
Project topProject = call.rel(0);
Project bottomProject = call.rel(1);
+ // Make sure both projects be LogicalProject.
+ if (topProject.getTraitSet().getTrait(ConventionTraitDef.INSTANCE) !=
Convention.NONE ||
--- End diff --
At first glance, it is non-intuitive that a Drill specific MergeProjectRule
returns False if a DRILL_LOGICAL convention is encountered. However,
currently, this rule only checks for the complex expression (e.g
convert_to_json), so your change is fine in the context of the current rule.
In future, would we consider allowing merging 2 DrillProjectRels ? (I think
yes).
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