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https://issues.apache.org/jira/browse/FLINK-4068?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15332448#comment-15332448
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ASF GitHub Bot commented on FLINK-4068:
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Github user fhueske commented on the issue:
https://github.com/apache/flink/pull/2102
This @wuchong, your approach looks good. I also found that the
`ReduceExpressionRules` had no effect due to the missing `RexExecutor`.
However, it seems that several tests of `ExpressionITCase` are failing with
this change. You can verify that the PR does not break the build by locally
running `mvn clean install`.
In addition, the added test should be changed as sketched in the comment.
Please let me know if you have questions.
Thanks, Fabian
> Move constant computations out of code-generated `flatMap` functions.
> ---------------------------------------------------------------------
>
> Key: FLINK-4068
> URL: https://issues.apache.org/jira/browse/FLINK-4068
> Project: Flink
> Issue Type: Improvement
> Components: Table API
> Affects Versions: 1.1.0
> Reporter: Fabian Hueske
>
> The generated functions for expressions of the Table API or SQL include
> constant computations.
> For instance the code generated for a predicate like:
> {code}
> myInt < (10 + 20)
> {code}
> looks roughly like:
> {code}
> public void flatMap(Row in, Collector<Row> out) {
> Integer in1 = in.productElement(1);
> int temp = 10 + 20;
> if (in1 < temp) {
> out.collect(in)
> }
> }
> {code}
> In this example the computation of {{temp}} is constant and could be moved
> out of the {{flatMap()}} method.
> The same might apply for generated function other than {{FlatMap}} as well.
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