flink-libraries/flink-table/src/main/scala/org/apache/flink/table/plan/nodes/logical/FlinkLogicalMinus.scala

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 * distributed with this work for additional information
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 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * 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.plan.nodes.logical

import org.apache.flink.table.plan.metadata.FlinkRelMetadataQuery
import org.apache.flink.table.plan.nodes.FlinkConventions

import org.apache.calcite.plan._
import org.apache.calcite.rel.RelNode
import org.apache.calcite.rel.convert.ConverterRule
import org.apache.calcite.rel.core.{Minus, SetOp}
import org.apache.calcite.rel.logical.LogicalMinus
import org.apache.calcite.rel.metadata.RelMetadataQuery

import java.util.{List => JList}

import scala.collection.JavaConverters._

class FlinkLogicalMinus(
    cluster: RelOptCluster,
    traitSet: RelTraitSet,
    inputs: JList[RelNode],
    all: Boolean)
  extends Minus(cluster, traitSet, inputs, all)
  with FlinkLogicalRel {

  override def copy(traitSet: RelTraitSet, inputs: JList[RelNode], all: Boolean): SetOp = {
    new FlinkLogicalMinus(cluster, traitSet, inputs, all)
  }

  override def computeSelfCost(planner: RelOptPlanner, mq: RelMetadataQuery): RelOptCost = {
    val children = this.getInputs.asScala
    children.foldLeft(planner.getCostFactory.makeCost(0, 0, 0)) { (cost, child) =>
      val rowCnt = mq.getRowCount(child)
      val rowSize = mq.getAverageRowSize(child)
      cost.plus(planner.getCostFactory.makeCost(rowCnt, rowCnt, rowCnt * rowSize))
    }
  }

  override def isDeterministic: Boolean = true
}

private class FlinkLogicalMinusConverter
  extends ConverterRule(
    classOf[LogicalMinus],
    Convention.NONE,
    FlinkConventions.LOGICAL,
    "FlinkLogicalMinusConverter") {

  override def convert(rel: RelNode): RelNode = {
    val minus = rel.asInstanceOf[LogicalMinus]
    val newInputs = minus.getInputs.asScala
        .map(input => RelOptRule.convert(input, FlinkConventions.LOGICAL)).asJava
    FlinkLogicalMinus.create(newInputs, minus.all)
  }
}

object FlinkLogicalMinus {
  val CONVERTER: ConverterRule = new FlinkLogicalMinusConverter()

  def create(inputs: JList[RelNode], all: Boolean): FlinkLogicalMinus = {
    val cluster = inputs.get(0).getCluster
    val traitSet = cluster.traitSetOf(Convention.NONE)
    // FIXME: FlinkRelMdDistribution requires the current RelNode to compute
    // the distribution trait, so we have to create FlinkLogicalMinus to
    // calculate the distribution trait
    val minus = new FlinkLogicalMinus(cluster, traitSet, inputs, all)
    val newTraitSet = FlinkRelMetadataQuery.traitSet(minus)
      .replace(FlinkConventions.LOGICAL).simplify()
    minus.copy(newTraitSet, minus.getInputs).asInstanceOf[FlinkLogicalMinus]
  }
}