xuzifu666 commented on code in PR #4267: URL: https://github.com/apache/calcite/pull/4267#discussion_r2046236743
########## core/src/main/java/org/apache/calcite/rel/rules/ExpandDisjunctionForTableRule.java: ########## @@ -0,0 +1,430 @@ +/* + * 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.metadata.RelMetadataQuery; +import org.apache.calcite.rel.type.RelDataTypeField; +import org.apache.calcite.rex.RexCall; +import org.apache.calcite.rex.RexInputRef; +import org.apache.calcite.rex.RexNode; +import org.apache.calcite.rex.RexTableInputRef; +import org.apache.calcite.rex.RexUtil; +import org.apache.calcite.tools.RelBuilder; +import org.apache.calcite.util.ControlFlowException; +import org.apache.calcite.util.ImmutableBitSet; + +import com.google.common.collect.Lists; + +import org.checkerframework.checker.nullness.qual.Nullable; +import org.immutables.value.Value; + +import java.util.HashMap; +import java.util.Iterator; +import java.util.List; +import java.util.Map; +import java.util.Set; + +/** + * Rule to expand disjunction for single table in condition of a {@link Filter} or {@link Join}, + * It makes sense to make this optimization part of the predicate pushdown. For example: + * + * <blockquote><pre>{@code + * select t1.name from t1, t2 + * where t1.id = t2.id + * and ( + * (t1.id > 20 and t2.height < 50) + * or + * (t1.weight < 200 and t2.sales > 100) + * ) + * }</pre></blockquote> + * + * <p>we can expand to obtain the condition + * + * <blockquote><pre>{@code + * select t1.name from t1, t2 + * where t1.id = t2.id + * and ( + * (t1.id > 20 and t2.height < 50) + * or + * (t1.weight < 200 and t2.sales > 100) + * ) + * and (t1.id > 20 or t1.weight < 200) + * and (t2.height < 50 or t2.sales > 100) + * }</pre></blockquote> + * + * <p>new generated predicates are redundant, but they could be pushed down to + * scan operator of t1/t2 and reduce the cardinality. + * + * <p>Note: This rule should only be applied once and it should be used before + * {@link CoreRules#FILTER_INTO_JOIN} and {@link CoreRules#JOIN_CONDITION_PUSH}. + * In order to avoid it interacting with other expression-related rules and causing + * an infinite loop, it is recommended to use it alone in HepPlanner first, + * and then do predicate pushdown. + * + * @see CoreRules#EXPAND_FILTER_DISJUNCTION_GLOBAL + * @see CoreRules#EXPAND_JOIN_DISJUNCTION_GLOBAL + */ [email protected] +public class ExpandDisjunctionForTableRule + extends RelRule<ExpandDisjunctionForTableRule.Config> + implements TransformationRule { + + /** + * Creates a ExpandDisjunctionForTableRule. + */ + protected ExpandDisjunctionForTableRule(Config config) { + super(config); + } + + @Override public void onMatch(RelOptRuleCall call) { + config.matchHandler().accept(this, call); + } + + /** + * Expand predicates for condition of a {@link Filter} or {@link Join}. + * + * @param condition Condition to be expanded in Filter or Join + * @param relNode The Filter or Join node + * @param fieldList The field list of the Filter or Join inputs. + * @param relBuilder Builder + * @param mq RelMetadataQuery, which is used to get the expression lineage + * + * @return The redundant predicate expanded from the condition parameter. It is formed by + * concatenating the predicates that can be pushed down to single table with AND. + */ + private RexNode apply( + RexNode condition, + RelNode relNode, + List<RelDataTypeField> fieldList, + RelBuilder relBuilder, + RelMetadataQuery mq) { + final Map<Integer, RexTableInputRef.RelTableRef> inputRefToTableRef = new HashMap<>(); + + ImmutableBitSet columnBits = RelOptUtil.InputFinder.bits(condition); + if (columnBits.isEmpty()) { + return condition; + } + + // For each table discover the conditions that refer to columns of that + // table (and refer to no other tables) + for (int columnBit : columnBits.asList()) { + Set<RexNode> exprLineage = + mq.getExpressionLineage( + relNode, + RexInputRef.of(columnBit, fieldList)); + // If mq.getExpressionLineage cannot get result, skip it + if (exprLineage == null) { + continue; + } + Set<RexTableInputRef.RelTableRef> relTableRefs = + RexUtil.gatherTableReferences(Lists.newArrayList(exprLineage)); + // If the column is computed by an expression that depends on multiple tables, skip it + if (relTableRefs.isEmpty() || relTableRefs.size() > 1) { Review Comment: Yes, my mistake, (relTableRefs.size != 1) equivalent to (relTableRefs.isEmpty() || relTableRefs.size() > 1)? or keep it as current~ -- This is an automated message from the Apache Git Service. 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