[GitHub] [spark] HeartSaVioR edited a comment on issue #27872: [SPARK-31115][SQL] Detect known Janino bug janino-compiler/janino#113 and apply workaround automatically as a fail-back via avoid using switch statement in generated code

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HeartSaVioR edited a comment on issue #27872: [SPARK-31115][SQL] Detect known Janino bug janino-compiler/janino#113 and apply workaround automatically as a fail-back via avoid using switch statement in generated code
URL: https://github.com/apache/spark/pull/27872#issuecomment-597911868
 
 
   It would be appreciated if we can elaborate the possible performance regression (even it's like a "thinking out loud"); "may" and "some cases" are too ambiguous.
   
   If the query doesn't fall into the case via hitting Janino issue, it shouldn't bring perf. regression, as it tries to generate code with `switch` and compiles first. If there's perf. regression here, it says I have some unintended mistake in fix which should be fixed.
   
   If the query fall into the case via hitting Janino issue, either the query has been failing or has been failing back to non-codegen. Taking alternative is definitely better than failing the query; the remaining one is whether using if ~ else if chain is worse than non-codegen.

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