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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-4715) Java compilation error for a query with large number of expressions
Date Fri, 17 Jun 2016 00:26:05 GMT

    [ https://issues.apache.org/jira/browse/DRILL-4715?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15335075#comment-15335075
] 

ASF GitHub Bot commented on DRILL-4715:
---------------------------------------

Github user amansinha100 commented on the issue:

    https://github.com/apache/drill/pull/521
  
    Just to be sure, I confirmed with @jinfengni that the new generated code would look like
the following:  (assume 100 expressions in the Project and limit of 50 exprs per block):
       doEval() { 
          {
              generated code for 50 expressions (by default)
          }
          doEval1();
      }
      doEval1() {
         {
             50 expressions
         }
         //  doEval2();  // if needed...each doEval_N() calls doEval_N+1()
      }


> Java compilation error for a query with large number of expressions
> -------------------------------------------------------------------
>
>                 Key: DRILL-4715
>                 URL: https://issues.apache.org/jira/browse/DRILL-4715
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Execution - Codegen
>            Reporter: Jinfeng Ni
>
> The following query would hit compilation error, when Drill generates and compiles the
run-time code. 
> Q1 :
> {code}
> select  expr1, expr2, expr3, ...., exprN
> from table
> {code} 
> In Q1, expr1, expr2, ..., exprN are non-trivial expression (in stead of simply column
reference), and N is big enough, then the run-time generated code may have a method which
goes beyond the 64k limit imposed by JVM. 
> This seems to be a regression from DRILL-3912 (Common subexpression elimination). CSE
tries to put as many expressions in one block as possible, to detect and eliminate as many
CSE as possible. However, this implies we may end up with big method with compilation error.
>     



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