dongjoon-hyun commented on a change in pull request #24495: [SPARK-27604][SQL]
Add filter reduction
URL: https://github.com/apache/spark/pull/24495#discussion_r282195808
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File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/expressions.scala
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@@ -55,99 +55,114 @@ object ConstantFolding extends Rule[LogicalPlan] {
}
/**
- * Substitutes [[Attribute Attributes]] which can be statically evaluated with
their corresponding
+ * Substitutes [[Expression Expressions]] which can be statically evaluated
with their corresponding
* value in conjunctive [[Expression Expressions]]
* eg.
* {{{
- * SELECT * FROM table WHERE i = 5 AND j = i + 3
- * ==> SELECT * FROM table WHERE i = 5 AND j = 8
+ * SELECT * FROM table WHERE i = 5 AND j = i + 3 => ... WHERE i
= 5 AND j = 8
+ * SELECT * FROM table WHERE abs(i) = 5 AND j <= abs(i) + 3 => ... WHERE
abs(i) = 5 AND j <= 8
* }}}
*
* Approach used:
- * - Populate a mapping of attribute => constant value by looking at all the
equals predicates
- * - Using this mapping, replace occurrence of the attributes with the
corresponding constant values
- * in the AND node.
+ * - Populate a mapping of expression => constant value by looking at all the
deterministic equals
+ * predicates
+ * - Using this mapping, replace occurrence of the expressions with the
corresponding constant
+ * values in the AND node.
*/
object ConstantPropagation extends Rule[LogicalPlan] with PredicateHelper {
Review comment:
Since new PR is created, we had better remove this change from this PR.
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