/* * 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 * limitations under the License. */ package org.apache.calcite.rel.core; import org.apache.calcite.plan.RelOptCluster; import org.apache.calcite.plan.RelOptCost; import org.apache.calcite.plan.RelOptPlanner; import org.apache.calcite.plan.RelOptUtil; import org.apache.calcite.plan.RelTraitSet; import org.apache.calcite.rel.BiRel; import org.apache.calcite.rel.RelInput; import org.apache.calcite.rel.RelNode; import org.apache.calcite.rel.RelWriter; import org.apache.calcite.rel.metadata.RelMetadataQuery; import org.apache.calcite.rel.type.RelDataType; import org.apache.calcite.sql.SemiJoinType; import org.apache.calcite.sql.validate.SqlValidatorUtil; import org.apache.calcite.util.ImmutableBitSet; import org.apache.calcite.util.Litmus; import com.google.common.collect.ImmutableList; import com.google.common.collect.ImmutableSet; import java.util.List; import java.util.Set; /** * A relational operator that performs nested-loop joins. * * <p>It behaves like a kind of {@link org.apache.calcite.rel.core.Join}, * but works by setting variables in its environment and restarting its * right-hand input. * * <p>Correlate is not a join since: typical rules should not match Correlate. * * <p>A Correlate is used to represent a correlated query. One * implementation strategy is to de-correlate the expression. * * <table> * <caption>Mapping of physical operations to logical ones</caption> * <tr><th>Physical operation</th><th>Logical operation</th></tr> * <tr><td>NestedLoops</td><td>Correlate(A, B, regular)</td></tr> * <tr><td>NestedLoopsOuter</td><td>Correlate(A, B, outer)</td></tr> * <tr><td>NestedLoopsSemi</td><td>Correlate(A, B, semi)</td></tr> * <tr><td>NestedLoopsAnti</td><td>Correlate(A, B, anti)</td></tr> * <tr><td>HashJoin</td><td>EquiJoin(A, B)</td></tr> * <tr><td>HashJoinOuter</td><td>EquiJoin(A, B, outer)</td></tr> * <tr><td>HashJoinSemi</td><td>SemiJoin(A, B, semi)</td></tr> * <tr><td>HashJoinAnti</td><td>SemiJoin(A, B, anti)</td></tr> * </table> * * @see CorrelationId */ public abstract class Correlate extends BiRel { //~ Instance fields -------------------------------------------------------- protected final CorrelationId correlationId; protected final ImmutableBitSet requiredColumns; protected final SemiJoinType joinType; //~ Constructors ----------------------------------------------------------- /** * Creates a Correlate. * * @param cluster Cluster this relational expression belongs to * @param left Left input relational expression * @param right Right input relational expression * @param correlationId Variable name for the row of left input * @param requiredColumns Set of columns that are used by correlation * @param joinType Join type */ protected Correlate( RelOptCluster cluster, RelTraitSet traits, RelNode left, RelNode right, CorrelationId correlationId, ImmutableBitSet requiredColumns, SemiJoinType joinType) { super(cluster, traits, left, right); this.joinType = joinType; this.correlationId = correlationId; this.requiredColumns = requiredColumns; } /** * Creates a Correlate by parsing serialized output. * * @param input Input representation */ public Correlate(RelInput input) { this( input.getCluster(), input.getTraitSet(), input.getInputs().get(0), input.getInputs().get(1), new CorrelationId((Integer) input.get("correlationId")), input.getBitSet("requiredColumns"), input.getEnum("joinType", SemiJoinType.class)); } //~ Methods ---------------------------------------------------------------- @Override public boolean isValid(Litmus litmus, Context context) { return super.isValid(litmus, context) && RelOptUtil.notContainsCorrelation(left, correlationId, litmus); } @Override public Correlate copy(RelTraitSet traitSet, List<RelNode> inputs) { assert inputs.size() == 2; return copy(traitSet, inputs.get(0), inputs.get(1), correlationId, requiredColumns, joinType); } public abstract Correlate copy(RelTraitSet traitSet, RelNode left, RelNode right, CorrelationId correlationId, ImmutableBitSet requiredColumns, SemiJoinType joinType); public SemiJoinType getJoinType() { return joinType; } @Override protected RelDataType deriveRowType() { switch (joinType) { case LEFT: case INNER: return SqlValidatorUtil.deriveJoinRowType(left.getRowType(), right.getRowType(), joinType.toJoinType(), getCluster().getTypeFactory(), null, ImmutableList.of()); case ANTI: case SEMI: return left.getRowType(); default: throw new IllegalStateException("Unknown join type " + joinType); } } @Override public RelWriter explainTerms(RelWriter pw) { return super.explainTerms(pw) .item("correlation", correlationId) .item("joinType", joinType.lowerName) .item("requiredColumns", requiredColumns.toString()); } /** * Returns the correlating expressions. * * @return correlating expressions */ public CorrelationId getCorrelationId() { return correlationId; } @Override public String getCorrelVariable() { return correlationId.getName(); } /** * Returns the required columns in left relation required for the correlation * in the right. * * @return columns in left relation required for the correlation in the right */ public ImmutableBitSet getRequiredColumns() { return requiredColumns; } @Override public Set<CorrelationId> getVariablesSet() { return ImmutableSet.of(correlationId); } @Override public RelOptCost computeSelfCost(RelOptPlanner planner, RelMetadataQuery mq) { double rowCount = mq.getRowCount(this); final double rightRowCount = right.estimateRowCount(mq); final double leftRowCount = left.estimateRowCount(mq); if (Double.isInfinite(leftRowCount) || Double.isInfinite(rightRowCount)) { return planner.getCostFactory().makeInfiniteCost(); } Double restartCount = mq.getRowCount(getLeft()); // RelMetadataQuery.getCumulativeCost(getRight()); does not work for // RelSubset, so we ask planner to cost-estimate right relation RelOptCost rightCost = planner.getCost(getRight(), mq); RelOptCost rescanCost = rightCost.multiplyBy(Math.max(1.0, restartCount - 1)); return planner.getCostFactory().makeCost( rowCount /* generate results */ + leftRowCount /* scan left results */, 0, 0).plus(rescanCost); } } // End Correlate.java