[CALCITE-4546] Change metadata dispatch to avoid registration of all RelNode subtypes

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.28.0
• Component/s: core
• Labels: pull-request-available
• Assignee: James Starr
• Reporter: James Starr
• Created: 22/Mar/21 16:45
• Updated: 20/Oct/21 05:24
• Resolved: 05/Oct/21 19:51

Description

Using JdbcTest.testJoinFiveWay, I ran the query six times then I took the last 3 results as reported by intellij.  I then repeated this 3 times.

After bench marking Janino, my prototype and using legacy java reflections, I found:

	Janino	Prototype	java reflection
Average	326.4444444	315.5555556	1525.888889
Standard Deviation	27.12983188	14.75729575	75.8476177

The prototype was a static code with out caching or cycle detection.  I latter added cycle detection and caching, but the results were with in one standard deviation.  So I didn't not follow up further.

I was doing the dispatch with instance of instead of scanning an array of known classes.

if(node instanceof ...){
  return handler.call((...) node);
} else if(node instanceof ...) {
  return handler.call((...) node);
}....

If janino compiler dispatch was changed to use instanceof, it would remove the requirement know all relnode subtypes. 

Issue Links

• causes: CALCITE-4834 JaninoRelMetadataProvider uses hardcoded class name
• links to: GitHub Pull Request #2376
• links to: GitHub Pull Request #2538