Wenchen Fan de6ad3dfa7 [SPARK-19309][SQL] disable common subexpression elimination for conditional expressions ... ## What changes were proposed in this pull request? As I pointed out in https://github.com/apache/spark/pull/15807#issuecomment-259143655 , the current subexpression elimination framework has a problem, it always evaluates all common subexpressions at the beginning, even they are inside conditional expressions and may not be accessed. Ideally we should implement it like scala lazy val, so we only evaluate it when it gets accessed at lease once. https://github.com/apache/spark/issues/15837 tries this approach, but it seems too complicated and may introduce performance regression. This PR simply stops common subexpression elimination for conditional expressions, with some cleanup. ## How was this patch tested? regression test Author: Wenchen Fan <wenchen@databricks.com> Closes #16659 from cloud-fan/codegen.		2017-01-23 13:31:26 +08:00
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src	[SPARK-19309][SQL] disable common subexpression elimination for conditional expressions	2017-01-23 13:31:26 +08:00
pom.xml	[SPARK-17807][CORE] split test-tags into test-JAR	2016-12-21 16:37:20 -08:00