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Posted to issues@spark.apache.org by "Apache Spark (JIRA)" <ji...@apache.org> on 2016/11/09 04:34:58 UTC
[jira] [Assigned] (SPARK-18376) Skip subexpression elimination for
conditional expressions
[ https://issues.apache.org/jira/browse/SPARK-18376?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Apache Spark reassigned SPARK-18376:
------------------------------------
Assignee: Apache Spark
> Skip subexpression elimination for conditional expressions
> ----------------------------------------------------------
>
> Key: SPARK-18376
> URL: https://issues.apache.org/jira/browse/SPARK-18376
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Reporter: Liang-Chi Hsieh
> Assignee: Apache Spark
>
> We should disallow subexpression elimination for expressions wrapped in conditional expressions such as {{If}}.
> Because for an example like this:
> {code}
> if (isNull(subexpr)) {
> ...
> } else {
> AssertNotNull(subexpr) // subexpr2
> ....
> SomeExpr(AssertNotNull(subexpr)) // SomeExpr(subexpr2)
> }
> {code}
> AssertNotNull(subexpr) will be recognized as a subexpression and evaluate even the else branch is never run. Under such cases, it possibly causes not excepted exception and performance regression.
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