[CALCITE-2363] Refactor RelShuttle not to depend on structures of RelNodes

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Labels: pull-request-available
• Assignee: Unassigned
• Reporter: Teruyoshi Zenmyo
• Created: 15/Jun/18 05:19
• Updated: 22/Feb/19 01:20

Description

Currently, RelShuttle implementations depends on the structures of RelNodes.

For instance, RelShuttleImp.visit(LogicalAggregate aggregate) knows the first element of getInput() is the next element to be visited. 

https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/rel/RelShuttleImpl.java#L75

 

By this refactoring, implementations of RelShuttle will become free from invoking super.visit methods.

https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/sql2rel/CorrelationReferenceFinder.java#L61

Issue Links

• links to: https://github.com/apache/calcite/pull/740