Liang-Chi Hsieh created SPARK-18376:
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Summary: 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
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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