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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 Thu, 16 Jun 2016 23:43:05 GMT

    [ https://issues.apache.org/jira/browse/DRILL-4715?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15334986#comment-15334986
] 

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

Github user amansinha100 commented on a diff in the pull request:

    https://github.com/apache/drill/pull/521#discussion_r67442811
  
    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/expr/SizedJBlock.java ---
    @@ -0,0 +1,48 @@
    +/**
    + * Licensed to the Apache Software Foundation (ASF) under one
    + * or more contributor license agreements.  See the NOTICE file
    + * distributed with this work for additional information
    + * regarding copyright ownership.  The ASF licenses this file
    + * to you under the Apache License, Version 2.0 (the
    + * "License"); you may not use this file except in compliance
    + * with the License.  You may obtain a copy of the License at
    + *
    + * http://www.apache.org/licenses/LICENSE-2.0
    + *
    + * Unless required by applicable law or agreed to in writing, software
    + * distributed under the License is distributed on an "AS IS" BASIS,
    + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    + * See the License for the specific language governing permissions and
    + * limitations under the License.
    + */
    +
    +package org.apache.drill.exec.expr;
    +
    +import com.sun.codemodel.JBlock;
    +
    +/**
    + * Uses this class to keep track # of Drill Logical Expressions that are
    + * put to JBlock.
    + */
    +public class SizedJBlock {
    +  private final JBlock block;
    --- End diff --
    
    Can you add a comment about why the jblock is a member variable rather than SizedJBlock
being a derived class of JBlock (which is a final class but is not obvious when looking at
this code). 


> 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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