zhengshiJ commented on code in PR #8947: URL: https://github.com/apache/incubator-doris/pull/8947#discussion_r854963106
########## fe/fe-core/src/main/java/org/apache/doris/statistics/StatsRecursiveDerive.java: ########## @@ -0,0 +1,52 @@ +// 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.doris.statistics; + +import org.apache.doris.planner.PlanNode; + + +public class StatsRecursiveDerive { + private StatsRecursiveDerive() {} + + public static StatsRecursiveDerive getStatsRecursiveDerive() { + return Inner.INSTANCE; + } + + private static class Inner { + private static final StatsRecursiveDerive INSTANCE = new StatsRecursiveDerive(); + } + + /** + * Recursively complete the derivation of statistics for this node and all its children + * @param node + * This parameter is an input and output parameter, + * which will store the derivation result of statistical information in the corresponding node + */ + public void statsRecursiveDerive(PlanNode node) { + if (node.getStatsDeriveResult().get().isStatsDerived()) { Review Comment: deleted ########## fe/fe-core/src/main/java/org/apache/doris/statistics/BaseStatsDerive.java: ########## @@ -0,0 +1,122 @@ +// 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.doris.statistics; + +import com.google.common.base.Preconditions; +import com.google.common.collect.Lists; +import org.apache.doris.analysis.Expr; +import org.apache.doris.planner.PlanNode; + +import java.util.ArrayList; +import java.util.Collections; +import java.util.List; +import java.util.Optional; + +public abstract class BaseStatsDerive { + // estimate of the output cardinality of this node; + // invalid: -1 + protected long cardinality = -1; + protected long limit = -1; + + protected List<Expr> conjuncts = Lists.newArrayList(); + protected List<Optional<StatsDeriveResult>> childrenStatsResult = Lists.newArrayList(); + + protected BaseStatsDerive init(PlanNode node) { + limit = node.getLimit(); + conjuncts.addAll(node.getConjuncts()); + + for (PlanNode childNode : node.getChildren()) { + childrenStatsResult.add(childNode.getStatsDeriveResult()); + } + return this; + } + + public abstract StatsDeriveResult deriveStats(); + + public boolean hasLimit() { + return limit > -1; + } + + protected void applyConjunctsSelectivity() { + if (cardinality == -1) { + return; + } + applySelectivity(); + } + + private void applySelectivity() { + double selectivity = computeSelectivity(); + Preconditions.checkState(cardinality >= 0); + long preConjunctCardinality = cardinality; + cardinality = Math.round(cardinality * selectivity); + // don't round cardinality down to zero for safety. + if (cardinality == 0 && preConjunctCardinality > 0) { + cardinality = 1; + } + } + + protected double computeSelectivity() { + for (Expr expr : conjuncts) { + expr.setSelectivity(); + } + return computeCombinedSelectivity(conjuncts); + } + + /** + * Returns the estimated combined selectivity of all conjuncts. Uses heuristics to + * address the following estimation challenges: + * 1. The individual selectivities of conjuncts may be unknown. + * 2. Two selectivities, whether known or unknown, could be correlated. Assuming + * independence can lead to significant underestimation. + * <p> + * The first issue is addressed by using a single default selectivity that is + * representative of all conjuncts with unknown selectivities. + * The second issue is addressed by an exponential backoff when multiplying each + * additional selectivity into the final result. + */ + static protected double computeCombinedSelectivity(List<Expr> conjuncts) { Review Comment: deleted -- 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. 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