silundong commented on code in PR #4619: URL: https://github.com/apache/calcite/pull/4619#discussion_r2549109867
########## core/src/main/java/org/apache/calcite/rel/rules/MarkToSemiOrAntiJoinRule.java: ########## @@ -0,0 +1,139 @@ +/* + * 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.RelOptRuleCall; +import org.apache.calcite.plan.RelOptUtil; +import org.apache.calcite.plan.RelRule; +import org.apache.calcite.rel.RelNode; +import org.apache.calcite.rel.core.Filter; +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.rex.RexCall; +import org.apache.calcite.rex.RexInputRef; +import org.apache.calcite.rex.RexNode; +import org.apache.calcite.sql.SqlKind; +import org.apache.calcite.tools.RelBuilder; +import org.apache.calcite.util.ImmutableBitSet; + +import org.immutables.value.Value; + +import java.util.ArrayList; +import java.util.List; + +import static org.apache.calcite.plan.RelOptUtil.conjunctions; + +/** + * Rule to simplify a mark join to semi join or anti join. + */ [email protected] +public class MarkToSemiOrAntiJoinRule + extends RelRule<MarkToSemiOrAntiJoinRule.Config> + implements TransformationRule { + + + /** Creates a MarkToSemiOrAntiJoinRule. */ + protected MarkToSemiOrAntiJoinRule(Config config) { + super(config); + } + + @Override public void onMatch(RelOptRuleCall call) { + final Project project = call.rel(0); + final Filter filter = call.rel(1); + final Join join = call.rel(2); + final RelBuilder builder = call.builder(); + + int markIndex = join.getRowType().getFieldCount() - 1; + ImmutableBitSet projectColumns = RelOptUtil.InputFinder.bits(project.getProjects(), null); + ImmutableBitSet filterColumns = RelOptUtil.InputFinder.bits(filter.getCondition()); + // Proj <- does not project marker + // Filter <- use marker in condition + // Join <- mark join + if (projectColumns.get(markIndex) || !filterColumns.get(markIndex)) { + return; + } + + // After decompose the filter condition by AND, there are only two cases to simplify: + // 1. only reference the marker, simplify to semi join + // 2. NOT(marker), and the join condition only contains IS [NOT] DISTINCT FROM, + // simplify to anti join + boolean toSemi = false; + boolean toAnti = false; + List<RexNode> filterConditions = RelOptUtil.conjunctions(filter.getCondition()); + List<RexNode> newFilterConditions = new ArrayList<>(); + for (RexNode condition : filterConditions) { + final ImmutableBitSet inputBits = RelOptUtil.InputFinder.bits(condition); + // marker not referenced + if (!inputBits.get(markIndex)) { + newFilterConditions.add(condition); + continue; + } + + // only marker referenced, to semi join + if (condition instanceof RexInputRef && !toAnti) { + toSemi = true; + continue; + } + // NOT(marker), and the join condition only contains IS [NOT] DISTINCT FROM, to anti join + if (condition instanceof RexCall + && condition.isA(SqlKind.NOT) + && ((RexCall) condition).getOperands().get(0) instanceof RexInputRef + && onlyContainsDistinctFrom(join.getCondition()) + && !toSemi) { + toAnti = true; + continue; + } + // other forms cannot be eliminated + return; + } + JoinRelType newJoinType = toSemi ? JoinRelType.SEMI : JoinRelType.ANTI; + RelNode result + = builder.push(join.getLeft()).push(join.getRight()) + .join(newJoinType, join.getCondition()) + .filter(newFilterConditions) + .project(project.getProjects()) + .build(); + call.transformTo(result); + } + + private static boolean onlyContainsDistinctFrom(RexNode condition) { + List<RexNode> conjunctions = conjunctions(condition); + for (RexNode expr : conjunctions) { + if (!expr.isA(SqlKind.IS_DISTINCT_FROM) && !expr.isA(SqlKind.IS_NOT_DISTINCT_FROM)) { + return false; + } + } + return true; + } + + /** Rule configuration. */ + @Value.Immutable + public interface Config extends RelRule.Config { + Config DEFAULT = ImmutableMarkToSemiOrAntiJoinRule.Config.of() + .withOperandSupplier(b1 -> + b1.operand(Project.class).oneInput(b2 -> + b2.operand(Filter.class).oneInput(b3 -> + b3.operand(Join.class).predicate(join -> join.getJoinType() == JoinRelType.MARK) Review Comment: Let me clarify my understanding: Firstly, the Umbra system's decorrelation should be completely based on the paper's algorithm. From the perspective of the paper algorithm, when decorrelate from Correlate→Join, the only change to the condition is the addition of natural join conditions for D attributes (IS NOT DISTINCT FROM), which ensures no NULL values are produced. Therefore, it is sufficient to evaluate the condition of the dependent join before decorrelation. This logic also applies to the TopDownGeneralDecorrelator in the current PR, as it is fully based on the paper's implementation. For TopDownGeneralDecorrelator, simplifying the MARK before decorrelation versus after decorrelation appears to make no difference. There is no necessity to match Correlate. Secondly, if I understand correctly, you pointed out that this rule needs to match Correlate so that it can be adapted later in RelDecorrelator. To my knowledge, the logic of RelDecorrelator does not guarantee that the condition change from Correlate→Join is limited to adding IS NOT DISTINCT FROM. Therefore, pre-simplifying Mark is unsafe for RelDecorrelator (if RelDecorrelator supports to handle MARK Correlate in future). So, for TopDownGeneralDecorrelator, there is no need to match Correlate; for RelDecorrelator, matching Correlate is unsafe. -- 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]
