SemiJoinProjectTransposeRule.java
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* 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
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* distributed under the License is distributed on an "AS IS" BASIS,
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package org.apache.calcite.rel.rules;
import org.apache.calcite.plan.RelOptRuleCall;
import org.apache.calcite.plan.RelRule;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.rel.core.Join;
import org.apache.calcite.rel.core.JoinRelType;
import org.apache.calcite.rel.core.Project;
import org.apache.calcite.rel.logical.LogicalJoin;
import org.apache.calcite.rel.logical.LogicalProject;
import org.apache.calcite.rel.type.RelDataType;
import org.apache.calcite.rel.type.RelDataTypeFactory;
import org.apache.calcite.rel.type.RelDataTypeField;
import org.apache.calcite.rex.RexBuilder;
import org.apache.calcite.rex.RexNode;
import org.apache.calcite.rex.RexProgram;
import org.apache.calcite.rex.RexProgramBuilder;
import org.apache.calcite.sql.validate.SqlValidatorUtil;
import org.apache.calcite.tools.RelBuilder;
import org.apache.calcite.util.Pair;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import org.immutables.value.Value;
import java.util.List;
import static java.util.Objects.requireNonNull;
/**
* Planner rule that pushes
* a {@link Join#isSemiJoin semi-join} down in a tree past
* a {@link org.apache.calcite.rel.core.Project}.
*
* <p>The intention is to trigger other rules that will convert
* {@code SemiJoin}s.
*
* <p>SemiJoin(LogicalProject(X), Y) → LogicalProject(SemiJoin(X, Y))
*
* @see org.apache.calcite.rel.rules.SemiJoinFilterTransposeRule
*/
@Value.Enclosing
public class SemiJoinProjectTransposeRule
extends RelRule<SemiJoinProjectTransposeRule.Config>
implements TransformationRule {
/** Creates a SemiJoinProjectTransposeRule. */
protected SemiJoinProjectTransposeRule(Config config) {
super(config);
}
//~ Methods ----------------------------------------------------------------
@Override public void onMatch(RelOptRuleCall call) {
final Join semiJoin = call.rel(0);
final Project project = call.rel(1);
// Convert the LHS semi-join keys to reference the child projection
// expression; all projection expressions must be RexInputRefs,
// otherwise, we wouldn't have created this semi-join.
// convert the semijoin condition to reflect the LHS with the project
// pulled up
RexNode newCondition = adjustCondition(project, semiJoin);
LogicalJoin newSemiJoin =
LogicalJoin.create(project.getInput(),
semiJoin.getRight(),
// No need to copy the hints, the framework would try to do that.
ImmutableList.of(),
newCondition,
ImmutableSet.of(), JoinRelType.SEMI);
// Create the new projection. Note that the projection expressions
// are the same as the original because they only reference the LHS
// of the semijoin and the semijoin only projects out the LHS
final RelBuilder relBuilder = call.builder();
relBuilder.push(newSemiJoin);
relBuilder.project(project.getProjects(), project.getRowType().getFieldNames());
call.transformTo(relBuilder.build());
}
/**
* Pulls the project above the semijoin and returns the resulting semijoin
* condition. As a result, the semijoin condition should be modified such
* that references to the LHS of a semijoin should now reference the
* children of the project that's on the LHS.
*
* @param project LogicalProject on the LHS of the semijoin
* @param semiJoin the semijoin
* @return the modified semijoin condition
*/
private static RexNode adjustCondition(Project project, Join semiJoin) {
// create two RexPrograms -- the bottom one representing a
// concatenation of the project and the RHS of the semijoin and the
// top one representing the semijoin condition
final RexBuilder rexBuilder = project.getCluster().getRexBuilder();
final RelDataTypeFactory typeFactory = rexBuilder.getTypeFactory();
final RelNode rightChild = semiJoin.getRight();
// for the bottom RexProgram, the input is a concatenation of the
// child of the project and the RHS of the semijoin
RelDataType bottomInputRowType =
SqlValidatorUtil.deriveJoinRowType(
project.getInput().getRowType(),
rightChild.getRowType(),
JoinRelType.INNER,
typeFactory,
null,
semiJoin.getSystemFieldList());
RexProgramBuilder bottomProgramBuilder =
new RexProgramBuilder(bottomInputRowType, rexBuilder);
// add the project expressions, then add input references for the RHS
// of the semijoin
for (Pair<RexNode, String> pair : project.getNamedProjects()) {
bottomProgramBuilder.addProject(pair.left, pair.right);
}
int nLeftFields = project.getInput().getRowType().getFieldCount();
List<RelDataTypeField> rightFields =
rightChild.getRowType().getFieldList();
int nRightFields = rightFields.size();
for (int i = 0; i < nRightFields; i++) {
final RelDataTypeField field = rightFields.get(i);
RexNode inputRef =
rexBuilder.makeInputRef(
field.getType(), i + nLeftFields);
bottomProgramBuilder.addProject(inputRef, field.getName());
}
RexProgram bottomProgram = bottomProgramBuilder.getProgram();
// input rowtype into the top program is the concatenation of the
// project and the RHS of the semijoin
RelDataType topInputRowType =
SqlValidatorUtil.deriveJoinRowType(
project.getRowType(),
rightChild.getRowType(),
JoinRelType.INNER,
typeFactory,
null,
semiJoin.getSystemFieldList());
RexProgramBuilder topProgramBuilder =
new RexProgramBuilder(
topInputRowType,
rexBuilder);
topProgramBuilder.addIdentity();
topProgramBuilder.addCondition(semiJoin.getCondition());
RexProgram topProgram = topProgramBuilder.getProgram();
// merge the programs and expand out the local references to form
// the new semijoin condition; it now references a concatenation of
// the project's child and the RHS of the semijoin
RexProgram mergedProgram =
RexProgramBuilder.mergePrograms(
topProgram,
bottomProgram,
rexBuilder);
return mergedProgram.expandLocalRef(
requireNonNull(mergedProgram.getCondition(),
() -> "mergedProgram.getCondition() for " + mergedProgram));
}
/** Rule configuration. */
@Value.Immutable
public interface Config extends RelRule.Config {
Config DEFAULT = ImmutableSemiJoinProjectTransposeRule.Config.of()
.withOperandFor(LogicalJoin.class, LogicalProject.class);
@Override default SemiJoinProjectTransposeRule toRule() {
return new SemiJoinProjectTransposeRule(this);
}
/** Defines an operand tree for the given classes. */
default Config withOperandFor(Class<? extends Join> joinClass,
Class<? extends Project> projectClass) {
return withOperandSupplier(b ->
b.operand(joinClass).predicate(Join::isSemiJoin).inputs(b2 ->
b2.operand(projectClass).anyInputs()))
.as(Config.class);
}
}
}