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https://issues.apache.org/jira/browse/CALCITE-2966?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16807720#comment-16807720
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Danny Chan commented on CALCITE-2966:
-------------------------------------
[~julian.feinauer] Can you please give your complete code snippet so i can
reproduce the error, the we can know if it is a bug, if it is, i will fix.
> Problem with Code Generation
> ----------------------------
>
> Key: CALCITE-2966
> URL: https://issues.apache.org/jira/browse/CALCITE-2966
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.20.0
> Reporter: Danny Chan
> Assignee: Danny Chan
> Priority: Major
> Fix For: 1.20.0
>
>
> From the mailing list:
> Hi all,
> I have some problems with the code generation from Linq4j which I'm unable to
> resolve myself.
> Basically, I want to translate a condition from Rex to a Linq4j expression to
> use it in generated code.
> In my example the Condition is from Match Recognize and in SQL is:
> `up."commission" > prev(up."commission")`.
>
> ```
> RexBuilder rexBuilder = new RexBuilder(implementor.getTypeFactory());
> RexProgramBuilder rexProgramBuilder = new
> RexProgramBuilder(physType.getRowType(), rexBuilder);
>
> rexProgramBuilder.addCondition(entry.getValue());
>
> final Expression condition =
> RexToLixTranslator.translateCondition(rexProgramBuilder.getProgram(),
> (JavaTypeFactory) getCluster().getTypeFactory(),
> builder2,
> inputGetter1,
> implementor.allCorrelateVariables,
> implementor.getConformance());
>
> builder2.add(Expressions.return_(null, condition));
> ```
>
> Here, the condition seems okay, it is: ">(PREV(UP.$4, 0), PREV(UP.$4, 1))",
> so it should be a comparison of two variables (I rewrite the PREV with a
> custom Input Getter".
> But, the generated code (for Janino) is:
>
> ```
> Object p1 = row_.get($L4J$C$0_1);
> org.apache.calcite.test.JdbcTest.Employee p0 =
> (org.apache.calcite.test.JdbcTest.Employee) p1;
> Object p3 = row_.get($L4J$C$1_1);
> org.apache.calcite.test.JdbcTest.Employee p2 =
> (org.apache.calcite.test.JdbcTest.Employee) p3;
> Object p5 = row_.get($L4J$C$0_1);
> org.apache.calcite.test.JdbcTest.Employee p4 =
> (org.apache.calcite.test.JdbcTest.Employee) p5;
> Object p7 = row_.get($L4J$C$1_1);
> org.apache.calcite.test.JdbcTest.Employee p6 =
> (org.apache.calcite.test.JdbcTest.Employee) p7;
> return p0.commission && p2.commission && p4.commission > p6.commission;
> ```
>
> This confuses me a lot as I do not know where the check for p0.commission and
> p2.commission comes from.
> It seems that Linq4j adds them as it expects these variables to be nullable,
> but I have no idea on how to avoid this.
> These fields are Numeric so I always get a compilation exception.
>
> Can someone help me with this issue?
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