HanumathRao commented on code in PR #3597: URL: https://github.com/apache/calcite/pull/3597#discussion_r1445133506
########## core/src/main/java/org/apache/calcite/rel/rules/SingleValueOptimizationRules.java: ########## @@ -0,0 +1,361 @@ +/* + * 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.rules; + +import org.apache.calcite.plan.RelOptRule; +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.core.Values; +import org.apache.calcite.rel.logical.LogicalValues; +import org.apache.calcite.rex.RexBuilder; +import org.apache.calcite.rex.RexInputRef; +import org.apache.calcite.rex.RexNode; +import org.apache.calcite.rex.RexShuttle; +import org.apache.calcite.rex.RexUtil; +import org.apache.calcite.sql.fun.SqlStdOperatorTable; +import org.apache.calcite.tools.RelBuilder; + +import org.checkerframework.checker.nullness.qual.Nullable; +import org.immutables.value.Value; + +import java.util.ArrayList; +import java.util.BitSet; +import java.util.List; +import java.util.function.BiFunction; +import java.util.function.Predicate; +import java.util.stream.Collectors; + +/** + * Collection of rules which simplify sections of query plan which are known to + * produce single row. + * + * <p>Conventionally, the way to represent a single row relational expression is + * with a {@link Values} that has one tuple. + * + * @see LogicalValues#createOneRow + */ +public abstract class SingleValueOptimizationRules { + + public static final RelOptRule JOIN_LEFT_INSTANCE = + SingleValueOptimizationRules.JoinLeftSingleRuleConfig.DEFAULT.toRule(); + + public static final RelOptRule JOIN_RIGHT_INSTANCE = + SingleValueOptimizationRules.JoinRightSingleRuleConfig.DEFAULT.toRule(); + + public static final RelOptRule JOIN_LEFT_PROJECT_INSTANCE = + SingleValueOptimizationRules.JoinLeftSingleValueRuleWithExprConfig.DEFAULT.toRule(); + + public static final RelOptRule JOIN_RIGHT_PROJECT_INSTANCE = + SingleValueOptimizationRules.JoinRightSingleValueRuleWithExprConfig.DEFAULT.toRule(); + + /** + * Transformer class to transform a single value nodes on either side of the join. + * This transformer contains the common code for all the SingleValueJoin rules. + */ + private static class SingleValueRelTransformer { + + private Join join; + private RelNode relNode; + private Predicate<Join> cannotTransform; + private BiFunction<RexNode, List<RexNode>, List<RexNode>> litTransformer; + private boolean valuesAsLeftChild; + private List<RexNode> literals; + + protected SingleValueRelTransformer( + Join join, List<RexNode> rexNodes, RelNode otherNode, + Predicate<Join> nonTransformable, boolean isValuesLeftChild, + BiFunction<RexNode, List<RexNode>, List<RexNode>> litTransformer) { + this.relNode = otherNode; + this.join = join; + this.cannotTransform = nonTransformable; + this.litTransformer = litTransformer; + this.valuesAsLeftChild = isValuesLeftChild; + this.literals = rexNodes; + } + + public @Nullable RelNode transform(RelBuilder relBuilder) { + if (cannotTransform.test(join)) { + return null; + } + BitSet bitSet = new BitSet(join.getRowType().getFieldCount()); + int end = valuesAsLeftChild + ? join.getLeft().getRowType().getFieldCount() + : join.getRowType().getFieldCount(); + + int start = valuesAsLeftChild + ? 0 + : join.getLeft().getRowType().getFieldCount(); + + bitSet.set(start, end); + RexNode trueNode = relBuilder.getRexBuilder().makeLiteral(true); + final RexNode filterCondition = + new ReplaceExprWithConstValue(bitSet, + literals, + (valuesAsLeftChild ? 0 : -1) * join.getLeft().getRowType().getFieldCount()) + .go(join.getCondition()); + + RexNode fixedCondition = + valuesAsLeftChild + ? RexUtil.shift(filterCondition, + -1 * join.getLeft().getRowType().getFieldCount()) + : filterCondition; + + List<RexNode> rexLiterals = litTransformer.apply(fixedCondition, literals); + relBuilder.push(relNode) + .filter(join.getJoinType().isOuterJoin() ? trueNode : fixedCondition); + + List<RexNode> rexNodes = relNode + .getRowType() + .getFieldList() + .stream() + .map(fld -> relBuilder.field(fld.getIndex())) + .collect(Collectors.toList()); + + List<RexNode> projects = new ArrayList<>(); + projects.addAll(valuesAsLeftChild ? rexLiterals : rexNodes); + projects.addAll(valuesAsLeftChild ? rexNodes : rexLiterals); + return relBuilder.project(projects).build(); + } + } + + /** + * A rex shuttle to replace field refs with constants from a {@link Values} row. + */ + private static class ReplaceExprWithConstValue extends RexShuttle { + + private final BitSet bitSet; + private final List<RexNode> fieldValues; + private final int offset; + ReplaceExprWithConstValue(BitSet bitSet, List<RexNode> values, int offset) { + this.bitSet = bitSet; + this.fieldValues = values; + this.offset = offset; + } + @Override public RexNode visitInputRef(RexInputRef inputRef) { + if (bitSet.get(inputRef.getIndex())) { + return this.fieldValues.get(inputRef.getIndex() + offset); + } + return super.visitInputRef(inputRef); + } + + public RexNode go(RexNode condition) { + return condition.accept(this); + } + } + + /** + * Abstract prune single value rule that implements SubstitutionRule interface. + */ + protected abstract static class PruneSingleValueRule + extends RelRule<PruneSingleValueRule.Config> + implements SubstitutionRule { + protected PruneSingleValueRule(PruneSingleValueRule.Config config) { + super(config); + } + + protected BiFunction<RexNode, List<RexNode>, List<RexNode>> + getRexTransformer(RexBuilder rexBuilder, + JoinRelType joinRelType) { + switch (joinRelType) { + case LEFT: + case RIGHT: + return (condition, rexLiterals) -> rexLiterals.stream().map(lit -> + rexBuilder.makeCall(SqlStdOperatorTable.CASE, condition, + lit, rexBuilder.makeNullLiteral(lit.getType()))).collect(Collectors.toList()); + default: + return (condition, rexLiterals) -> rexLiterals.stream().collect(Collectors.toList()); + } + } + + static final Predicate<Join> elibilityPredicate(boolean isLeft) { Review Comment: I thought about it but left it for now as I plan to add explore for semi join and anti join in a different JIRA. -- This is an automated message from the Apache Git Service. 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