exec/java-exec/src/main/java/org/apache/drill/exec/planner/physical/MergeJoinPrel.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * 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
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
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package org.apache.drill.exec.planner.physical;

import java.io.IOException;
import java.util.List;

import org.apache.calcite.rel.core.Join;
import org.apache.drill.common.logical.data.JoinCondition;
import org.apache.drill.exec.physical.base.PhysicalOperator;
import org.apache.drill.exec.physical.config.MergeJoinPOP;
import org.apache.drill.exec.physical.impl.join.JoinUtils;
import org.apache.drill.exec.physical.impl.join.JoinUtils.JoinCategory;
import org.apache.drill.exec.planner.cost.DrillCostBase;
import org.apache.drill.exec.planner.cost.DrillCostBase.DrillCostFactory;
import org.apache.drill.exec.record.BatchSchema.SelectionVectorMode;
import org.apache.calcite.rel.InvalidRelException;
import org.apache.calcite.rel.core.JoinRelType;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.rel.metadata.RelMetadataQuery;
import org.apache.calcite.plan.RelOptCluster;
import org.apache.calcite.plan.RelOptCost;
import org.apache.calcite.plan.RelOptPlanner;
import org.apache.calcite.plan.RelTraitSet;
import org.apache.calcite.rex.RexNode;

import com.google.common.collect.Lists;

public class MergeJoinPrel  extends JoinPrel {

  /** Creates a MergeJoiPrel. */
  public MergeJoinPrel(RelOptCluster cluster, RelTraitSet traits, RelNode left, RelNode right, RexNode condition,
      JoinRelType joinType) throws InvalidRelException {
    super(cluster, traits, left, right, condition, joinType);
    joincategory = JoinUtils.getJoinCategory(left, right, condition, leftKeys, rightKeys, filterNulls);
  }

  public MergeJoinPrel(RelOptCluster cluster, RelTraitSet traits, RelNode left, RelNode right, RexNode condition,
                       JoinRelType joinType, boolean semijoin) throws InvalidRelException {
    super(cluster, traits, left, right, condition, joinType, semijoin);
    joincategory = JoinUtils.getJoinCategory(left, right, condition, leftKeys, rightKeys, filterNulls);
  }

  @Override
  public Join copy(RelTraitSet traitSet, RexNode conditionExpr, RelNode left, RelNode right, JoinRelType joinType, boolean semiJoinDone) {
    try {
      return new MergeJoinPrel(this.getCluster(), traitSet, left, right, conditionExpr, joinType);
    }catch (InvalidRelException e) {
      throw new AssertionError(e);
    }
  }

  @Override
  public RelOptCost computeSelfCost(RelOptPlanner planner, RelMetadataQuery mq) {
    if (PrelUtil.getSettings(getCluster()).useDefaultCosting()) {
      return super.computeSelfCost(planner, mq).multiplyBy(.1);
    }
    if (joincategory == JoinCategory.CARTESIAN || joincategory == JoinCategory.INEQUALITY
        || getJoinType() == JoinRelType.FULL) {
      return planner.getCostFactory().makeInfiniteCost();
    }
    double leftRowCount = mq.getRowCount(this.getLeft());
    double rightRowCount = mq.getRowCount(this.getRight());
    // cost of evaluating each leftkey=rightkey join condition
    double joinConditionCost = DrillCostBase.COMPARE_CPU_COST * this.getLeftKeys().size();
    double cpuCost = joinConditionCost * (leftRowCount + rightRowCount);
    DrillCostFactory costFactory = (DrillCostFactory) planner.getCostFactory();
    return costFactory.makeCost(leftRowCount + rightRowCount, cpuCost, 0, 0);
  }

  @Override
  public PhysicalOperator getPhysicalOperator(PhysicalPlanCreator creator) throws IOException {
    final List<String> fields = getRowType().getFieldNames();
    assert isUnique(fields);

    final int leftCount = left.getRowType().getFieldCount();
    final List<String> leftFields = fields.subList(0, leftCount);
    final List<String> rightFields = fields.subList(leftCount, fields.size());

    PhysicalOperator leftPop = ((Prel)left).getPhysicalOperator(creator);
    PhysicalOperator rightPop = ((Prel)right).getPhysicalOperator(creator);

    JoinRelType jtype = this.getJoinType();

    List<JoinCondition> conditions = Lists.newArrayList();

    buildJoinConditions(conditions, leftFields, rightFields, leftKeys, rightKeys);

    MergeJoinPOP mjoin = new MergeJoinPOP(leftPop, rightPop, conditions, jtype);
    return creator.addMetadata(this, mjoin);

  }

  @Override
  public SelectionVectorMode[] getSupportedEncodings() {
    // currently, MergeJoin operator is not handling incoming batch containing SV2 or SV4, so
    // it requires a SVRemover
    return SelectionVectorMode.DEFAULT;
  }

  @Override
  public SelectionVectorMode getEncoding() {
    return SelectionVectorMode.NONE;
  }


}