[CALCITE-2703] Reduce code generation and class loading overhead when executing queries in the EnumerableConvention

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.17.0
• Fix Version/s: 1.19.0
• Component/s: core
• Labels: performance pull-request-available
• Assignee: Stamatis Zampetakis
• Reporter: Stamatis Zampetakis
• Created: 23/Nov/18 15:22
• Updated: 27/Jul/20 17:19
• Resolved: 28/Feb/19 16:00

Description

The queries using Calcite's EnumerableConvention always end-up generating new java classes at runtime (using Janino) that are then instantiated using reflection. This combination of class generation and class loading introduces a big overhead in query response time.

A quick profiling on our Company's internal test suite consisting in 4000 tests with roughly 430000 SQL queries passing through Calcite we observed that a big amount of time is spend on code generation and class loading making the EnumerableInterpretable#toBindable method a performance bottleneck. 

Among the 430000 SQL queries there are many duplicates which are going to lead to the generation of exactly the same code Java. Introducing, a small cache at the level of EnumerableInterpretable class could avoid generating and loading the same code over and over again.

A simple implementation based on Guava improved the overall execution time of the afforementioned test suite by more than 50%.

 

 

Issue Links

• is blocked by: CALCITE-2701 Ensure that the "Baz" classes generated by Janino are thread-safe
• is related to: CALCITE-2859 Centralize Calcite system properties
• relates to: CALCITE-4144 Reduce code generation and class loading overhead when getScalar in JaninoRexCompiler.
• links to: GitHub Pull Request #950