Kikyou1997 commented on code in PR #11179: URL: https://github.com/apache/doris/pull/11179#discussion_r929637321
########## fe/fe-core/src/main/java/org/apache/doris/nereids/stats/HashJoinEstimation.java: ########## @@ -0,0 +1,155 @@ +// 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.nereids.stats; + +import org.apache.doris.common.CheckedMath; +import org.apache.doris.nereids.trees.expressions.Expression; +import org.apache.doris.nereids.trees.expressions.Slot; +import org.apache.doris.nereids.trees.expressions.SlotReference; +import org.apache.doris.nereids.trees.plans.JoinType; +import org.apache.doris.nereids.util.ExpressionUtils; +import org.apache.doris.statistics.ColumnStats; +import org.apache.doris.statistics.StatsDeriveResult; + +import com.google.common.base.Preconditions; + +import java.util.List; +import java.util.Map; + +/** + * Estimate hash join stats. + * TODO: Update other props in the ColumnStats properly. + */ +public class HashJoinEstimation { + + /** + * Do estimate. + */ + public static StatsDeriveResult estimate(StatsDeriveResult leftStats, StatsDeriveResult rightStats, + Expression eqCondition, JoinType joinType) { + StatsDeriveResult statsDeriveResult = new StatsDeriveResult(leftStats); + statsDeriveResult.merge(rightStats); + List<Expression> eqConjunctList = ExpressionUtils.extractConjunct(eqCondition); + long rowCount = -1; + if (joinType.isSemiOrAntiJoin()) { + rowCount = getSemiJoinRowCount(leftStats, rightStats, eqConjunctList, joinType); + } else if (joinType.isInnerJoin() || joinType.isOuterJoin()) { + rowCount = getJoinRowCount(leftStats, rightStats, eqConjunctList, joinType); + } else { + throw new RuntimeException("joinType is not supported"); + } + statsDeriveResult.setRowCount(rowCount); + return statsDeriveResult; + } + + private static long getSemiJoinRowCount(StatsDeriveResult leftStats, StatsDeriveResult rightStats, + List<Expression> eqConjunctList, JoinType joinType) { + long rowCount; + if (JoinType.RIGHT_SEMI_JOIN.equals(joinType) || JoinType.RIGHT_ANTI_JOIN.equals(joinType)) { + if (rightStats.getRowCount() == -1) { + return -1; + } + rowCount = rightStats.getRowCount(); + } else { + if (leftStats.getRowCount() == -1) { + return -1; + } + rowCount = leftStats.getRowCount(); + } + Map<Slot, ColumnStats> leftSlotToColStats = leftStats.getSlotRefToColumnStatsMap(); + Map<Slot, ColumnStats> rightSlotToColStats = rightStats.getSlotRefToColumnStatsMap(); + double minSelectivity = 1.0; + for (Expression eqJoinPredicate : eqConjunctList) { + long lhsNdv = leftSlotToColStats.get(eqJoinPredicate.child(0)).getNdv(); + lhsNdv = Math.min(lhsNdv, leftStats.getRowCount()); + long rhsNdv = rightSlotToColStats.get(eqJoinPredicate.child(1)).getNdv(); + rhsNdv = Math.min(rhsNdv, rightStats.getRowCount()); + // Skip conjuncts with unknown NDV on either side. + if (lhsNdv == -1 || rhsNdv == -1) { + continue; + } + // TODO: Do we need NULL_AWARE_LEFT_ANTI_JOIN type as stale optimizer? + double selectivity = 1.0; + switch (joinType) { + case LEFT_SEMI_JOIN: { + selectivity = (double) Math.min(lhsNdv, rhsNdv) / (double) (lhsNdv); + break; + } + case RIGHT_SEMI_JOIN: { + selectivity = (double) Math.min(lhsNdv, rhsNdv) / (double) (rhsNdv); + break; + } + case LEFT_ANTI_JOIN: + selectivity = (double) (lhsNdv > rhsNdv ? (lhsNdv - rhsNdv) : lhsNdv) / (double) lhsNdv; + break; + case RIGHT_ANTI_JOIN: { + selectivity = (double) (rhsNdv > lhsNdv ? (rhsNdv - lhsNdv) : rhsNdv) / (double) rhsNdv; + break; + } + default: + throw new RuntimeException("joinType is not supported"); + } + minSelectivity = Math.min(minSelectivity, selectivity); + } + Preconditions.checkState(rowCount != -1); + return Math.round(rowCount * minSelectivity); + } + + private static long getJoinRowCount(StatsDeriveResult leftStats, StatsDeriveResult rightStats, + List<Expression> eqConjunctList, JoinType joinType) { + long lhsCard = leftStats.getRowCount(); + long rhsCard = rightStats.getRowCount(); + Map<Slot, ColumnStats> leftSlotToColumnStats = leftStats.getSlotRefToColumnStatsMap(); + Map<Slot, ColumnStats> rightSlotToColumnStats = rightStats.getSlotRefToColumnStatsMap(); + if (lhsCard == -1 || rhsCard == -1) { + return lhsCard; + } + long result = -1; + for (Expression eqJoinConjunct : eqConjunctList) { + Expression left = eqJoinConjunct.child(0); + if (!(left instanceof SlotReference)) { Review Comment: Will support such case in the future, I guess there doesn't have such join condition in tpch -- This is an automated message from the Apache Git Service. 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