[CALCITE-1100] If ReduceExpressionsRule generates the same plan, the original plan stops triggering other rules

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.7.0
• Component/s: core
• Assignee: Julian Hyde
• Reporter: Sean Hsuan-Yi Chu
• Created: 25/Feb/16 00:48
• Updated: 22/Mar/16 01:18
• Resolved: 25/Feb/16 23:58

Description

Calcite allows users to implement a customized RelOptPlanner#Executor to determine how a RexNode is reduced to another.

In some cases, the customized RelOptPlanner#Executor might decide not to do any reduction for a given RexNode (i.e., constExps2 and reducedValues are the same in [1]).

However, for these cases, Calcite is not aware of the new plan is equivalent to the old one, but just go ahead to force the Importance of the old/new plan as ZERO [2]. After the Importance becomes ZERO, the original plan stops triggering other rules

[1] github code: https://github.com/apache/calcite/blob/f55d10c147746d6299fb713adc184576380a1f49/core/src/main/java/org/apache/calcite/rel/rules/ReduceExpressionsRule.java#L508

[2] github code:
https://github.com/apache/calcite/blob/f55d10c147746d6299fb713adc184576380a1f49/core/src/main/java/org/apache/calcite/rel/rules/ReduceExpressionsRule.java#L184