Cheng Hao a20fea9881 [Spark-1461] Deferred Expression Evaluation (short-circuit evaluation) ... This patch unify the foldable & nullable interface for Expression. 1) Deterministic-less UDF (like Rand()) can not be folded. 2) Short-circut will significantly improves the performance in Expression Evaluation, however, the stateful UDF should not be ignored in a short-circuit evaluation(e.g. in expression: col1 > 0 and row_sequence() < 1000, row_sequence() can not be ignored even if col1 > 0 is false) I brought an concept of DeferredObject from Hive, which has 2 kinds of children classes (EagerResult / DeferredResult), the former requires triggering the evaluation before it's created, while the later trigger the evaluation when first called its get() method. Author: Cheng Hao <hao.cheng@intel.com> Closes #446 from chenghao-intel/expression_deferred_evaluation and squashes the following commits: d2729de [Cheng Hao] Fix the codestyle issues a08f09c [Cheng Hao] fix bug in or/and short-circuit evaluation af2236b [Cheng Hao] revert the short-circuit expression evaluation for IF b7861d2 [Cheng Hao] Add Support for Deferred Expression Evaluation		2014-05-15 22:12:34 -07:00
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src	[Spark-1461] Deferred Expression Evaluation (short-circuit evaluation)	2014-05-15 22:12:34 -07:00
pom.xml	Improved build configuration	2014-04-28 22:51:46 -07:00