org.apache.flink.table.planner.plan.rules.logical.FlinkPruneEmptyRules.scala Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* to you under the Apache License, Version 2.0 (the
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* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
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package org.apache.flink.table.planner.plan.rules.logical
import org.apache.calcite.plan.RelOptRule.{any, none, operand, some}
import org.apache.calcite.plan.{RelOptRule, RelOptRuleCall}
import org.apache.calcite.rel.RelNode
import org.apache.calcite.rel.core.{Join, JoinRelType, Values}
object FlinkPruneEmptyRules {
/**
* This rule is copied from Calcite's
* [[org.apache.calcite.rel.rules.PruneEmptyRules#JOIN_RIGHT_INSTANCE]].
*
* Modification:
* - Handles ANTI join specially.
*
* Rule that converts a [[Join]] to empty if its right child is empty.
*
* Examples:
*
*
* - Join(Scan(Emp), Empty, INNER) becomes Empty
*
*/
val JOIN_RIGHT_INSTANCE: RelOptRule = new RelOptRule(
operand(classOf[Join],
some(operand(classOf[RelNode], any),
operand(classOf[Values], none))),
"FlinkPruneEmptyRules(right)") {
override def matches(call: RelOptRuleCall): Boolean = {
val right: Values = call.rel(2)
Values.IS_EMPTY.apply(right)
}
override def onMatch(call: RelOptRuleCall): Unit = {
val join: Join = call.rel(0)
join.getJoinType match {
case JoinRelType.ANTI =>
// "select * from emp where deptno not in (select deptno from dept where 1=0)"
// return emp
call.transformTo(call.builder().push(join.getLeft).build)
case _ =>
if (join.getJoinType.generatesNullsOnRight) {
// "select * from emp left join dept" is not necessarily empty if dept is empty
} else {
call.transformTo(call.builder.push(join).empty.build)
}
}
}
}
}