HanumathRao commented on code in PR #3597: URL: https://github.com/apache/calcite/pull/3597#discussion_r1446459398
########## core/src/main/java/org/apache/calcite/rel/rules/SingleValueOptimizationRules.java: ########## @@ -0,0 +1,329 @@ +/* + * 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.apache.calcite.util.ImmutableBitSet; + +import org.checkerframework.checker.nullness.qual.Nullable; +import org.immutables.value.Value; + +import java.util.ArrayList; +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 final Join join; + private final RelNode relNode; + private final Predicate<Join> cannotTransform; + private final BiFunction<RexNode, List<RexNode>, List<RexNode>> litTransformer; + private final boolean valuesAsLeftChild; + private final 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; + } + int end = valuesAsLeftChild + ? join.getLeft().getRowType().getFieldCount() + : join.getRowType().getFieldCount(); + + int start = valuesAsLeftChild + ? 0 + : join.getLeft().getRowType().getFieldCount(); + ImmutableBitSet bitSet = ImmutableBitSet.range(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 ImmutableBitSet bitSet; + private final List<RexNode> fieldValues; + private final int offset; + ReplaceExprWithConstValue(ImmutableBitSet 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) -> new ArrayList<>(rexLiterals); + } + } + + protected void onMatch(RelOptRuleCall call, Values values, + @Nullable Project project, Join join, + RelNode other, boolean isLeft) { + Predicate<Join> predicate = elibilityPredicate(isLeft); + List<RexNode> rexNodes; + if (project != null) { + ImmutableBitSet bitSet = ImmutableBitSet.range(0, values.getRowType().getFieldCount()); + RexShuttle shuttle = + new ReplaceExprWithConstValue(bitSet, + new ArrayList<>(values.getTuples().get(0)), + 0); + + rexNodes = project.getProjects().stream() + .map(shuttle::apply) + .collect(Collectors.toList()); + } else { + rexNodes = new ArrayList<>(values.tuples.get(0)); + } + RelBuilder relBuilder = call.builder(); + RelNode transformed = + new SingleValueRelTransformer(join, rexNodes, other, + predicate, isLeft, getRexTransformer(relBuilder.getRexBuilder(), + join.getJoinType())).transform(relBuilder); + if (transformed != null) { + call.transformTo(transformed); + } + } + + static Predicate<Join> elibilityPredicate(boolean isLeft) { + if (isLeft) { + return jn -> jn.getJoinType() == JoinRelType.LEFT + || jn.getJoinType() == JoinRelType.FULL + || jn.getJoinType() == JoinRelType.ANTI; + } else { + return jn -> jn.getJoinType() == JoinRelType.RIGHT + || jn.getJoinType() == JoinRelType.FULL + || jn.getJoinType() == JoinRelType.ANTI; + } + } + + @Override public boolean autoPruneOld() { + return true; + } + + /** Rule configuration. */ + protected interface Config extends RelRule.Config { + @Override PruneSingleValueRule toRule(); + } + } + + /** Configuration for a rule that simplifies join node with constant row on its right input. */ + @Value.Immutable + interface JoinRightSingleRuleConfig extends PruneSingleValueRule.Config { + JoinRightSingleRuleConfig DEFAULT = ImmutableJoinRightSingleRuleConfig.of() + .withOperandSupplier(b0 -> + b0.operand(Join.class).inputs( + b1 -> b1.operand(RelNode.class).anyInputs(), + b2 -> b2.operand(Values.class).predicate(Values::isSingleValue).noInputs())) + .withDescription("PruneJoinSingleValue(right)"); + + @Override default SingleValueOptimizationRules.PruneSingleValueRule toRule() { + return new SingleValueOptimizationRules.PruneSingleValueRule(this) { + @Override public void onMatch(RelOptRuleCall call) { + final Join join = call.rel(0); + final Values values = call.rel(2); + final RelNode other = call.rel(1); + onMatch(call, values, null, join, other, false); + } + }; + } + } + + /** Configuration for a rule that simplifies join node with constant row on its left input. */ + @Value.Immutable + interface JoinLeftSingleRuleConfig extends PruneSingleValueRule.Config { + JoinLeftSingleRuleConfig DEFAULT = ImmutableJoinLeftSingleRuleConfig.of() + .withOperandSupplier(b0 -> + b0.operand(Join.class).inputs( + b1 -> b1.operand(Values.class).predicate(Values::isSingleValue).noInputs(), + b2 -> b2.operand(RelNode.class).anyInputs())) + .withDescription("PruneJoinSingleValueRule(left)"); + + @Override default SingleValueOptimizationRules.PruneSingleValueRule toRule() { + return new SingleValueOptimizationRules.PruneSingleValueRule(this) { + @Override public void onMatch(RelOptRuleCall call) { + final Join join = call.rel(0); + final Values values = call.rel(1); + final RelNode other = call.rel(2); + onMatch(call, values, null, join, other, true); + } + }; + } + } + + /** Configuration for a rule that simplifies join node with a project on a constant row Review Comment: _Is it a projection applied to a VALUES node?_ Yes, here project on a constant row is same as the projection applied to a VALUES node. The pattern with project on VALUES node is handled here because VALUES node can only have static constants (RexLiteral) whereas there will be use cases like current_timestamp which are more of a dynamic constants which are as part of the project node. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
