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io.trino.cost.JoinStatsRule Maven / Gradle / Ivy
/*
* Licensed 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 io.trino.cost;
import com.google.common.annotations.VisibleForTesting;
import io.trino.Session;
import io.trino.cost.StatsCalculator.Context;
import io.trino.matching.Pattern;
import io.trino.sql.ir.Comparison;
import io.trino.sql.ir.Expression;
import io.trino.sql.planner.Symbol;
import io.trino.sql.planner.plan.JoinNode;
import io.trino.sql.planner.plan.JoinNode.EquiJoinClause;
import io.trino.util.MoreMath;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.collect.ImmutableList.toImmutableList;
import static com.google.common.collect.Sets.difference;
import static io.trino.SystemSessionProperties.getJoinMultiClauseIndependenceFactor;
import static io.trino.cost.FilterStatsCalculator.UNKNOWN_FILTER_COEFFICIENT;
import static io.trino.cost.PlanNodeStatsEstimateMath.estimateCorrelatedConjunctionRowCount;
import static io.trino.cost.SymbolStatsEstimate.buildFrom;
import static io.trino.sql.ir.Comparison.Operator.EQUAL;
import static io.trino.sql.ir.IrUtils.extractConjuncts;
import static io.trino.sql.planner.plan.Patterns.join;
import static io.trino.util.MoreMath.firstNonNaN;
import static java.lang.Double.NaN;
import static java.lang.Double.isNaN;
import static java.lang.Math.min;
import static java.util.Comparator.comparingDouble;
import static java.util.Objects.requireNonNull;
public class JoinStatsRule
extends SimpleStatsRule
{
private static final Pattern PATTERN = join();
private static final double DEFAULT_UNMATCHED_JOIN_COMPLEMENT_NDVS_COEFFICIENT = 0.5;
private final FilterStatsCalculator filterStatsCalculator;
private final StatsNormalizer normalizer;
private final double unmatchedJoinComplementNdvsCoefficient;
public JoinStatsRule(FilterStatsCalculator filterStatsCalculator, StatsNormalizer normalizer)
{
this(filterStatsCalculator, normalizer, DEFAULT_UNMATCHED_JOIN_COMPLEMENT_NDVS_COEFFICIENT);
}
@VisibleForTesting
JoinStatsRule(FilterStatsCalculator filterStatsCalculator, StatsNormalizer normalizer, double unmatchedJoinComplementNdvsCoefficient)
{
super(normalizer);
this.filterStatsCalculator = requireNonNull(filterStatsCalculator, "filterStatsCalculator is null");
this.normalizer = normalizer;
this.unmatchedJoinComplementNdvsCoefficient = unmatchedJoinComplementNdvsCoefficient;
}
@Override
public Pattern getPattern()
{
return PATTERN;
}
@Override
protected Optional doCalculate(JoinNode node, Context context)
{
PlanNodeStatsEstimate leftStats = context.statsProvider().getStats(node.getLeft());
PlanNodeStatsEstimate rightStats = context.statsProvider().getStats(node.getRight());
PlanNodeStatsEstimate crossJoinStats = crossJoinStats(node, leftStats, rightStats);
return switch (node.getType()) {
case INNER -> Optional.of(computeInnerJoinStats(node, crossJoinStats, context.session()));
case LEFT -> Optional.of(computeLeftJoinStats(node, leftStats, rightStats, crossJoinStats, context.session()));
case RIGHT -> Optional.of(computeRightJoinStats(node, leftStats, rightStats, crossJoinStats, context.session()));
case FULL -> Optional.of(computeFullJoinStats(node, leftStats, rightStats, crossJoinStats, context.session()));
};
}
@SuppressWarnings("ArgumentSelectionDefectChecker")
private PlanNodeStatsEstimate computeFullJoinStats(
JoinNode node,
PlanNodeStatsEstimate leftStats,
PlanNodeStatsEstimate rightStats,
PlanNodeStatsEstimate crossJoinStats,
Session session)
{
PlanNodeStatsEstimate rightJoinComplementStats = calculateJoinComplementStats(node.getFilter(), flippedCriteria(node), rightStats, leftStats);
return addJoinComplementStats(
rightStats,
computeLeftJoinStats(node, leftStats, rightStats, crossJoinStats, session),
rightJoinComplementStats);
}
private PlanNodeStatsEstimate computeLeftJoinStats(
JoinNode node,
PlanNodeStatsEstimate leftStats,
PlanNodeStatsEstimate rightStats,
PlanNodeStatsEstimate crossJoinStats,
Session session)
{
PlanNodeStatsEstimate innerJoinStats = computeInnerJoinStats(node, crossJoinStats, session);
PlanNodeStatsEstimate leftJoinComplementStats = calculateJoinComplementStats(node.getFilter(), node.getCriteria(), leftStats, rightStats);
return addJoinComplementStats(
leftStats,
innerJoinStats,
leftJoinComplementStats);
}
@SuppressWarnings("ArgumentSelectionDefectChecker")
private PlanNodeStatsEstimate computeRightJoinStats(
JoinNode node,
PlanNodeStatsEstimate leftStats,
PlanNodeStatsEstimate rightStats,
PlanNodeStatsEstimate crossJoinStats,
Session session)
{
PlanNodeStatsEstimate innerJoinStats = computeInnerJoinStats(node, crossJoinStats, session);
PlanNodeStatsEstimate rightJoinComplementStats = calculateJoinComplementStats(node.getFilter(), flippedCriteria(node), rightStats, leftStats);
return addJoinComplementStats(
rightStats,
innerJoinStats,
rightJoinComplementStats);
}
private PlanNodeStatsEstimate computeInnerJoinStats(JoinNode node, PlanNodeStatsEstimate crossJoinStats, Session session)
{
List equiJoinCriteria = node.getCriteria();
if (equiJoinCriteria.isEmpty()) {
if (node.getFilter().isEmpty()) {
return crossJoinStats;
}
// TODO: this might explode stats
return filterStatsCalculator.filterStats(crossJoinStats, node.getFilter().get(), session);
}
PlanNodeStatsEstimate equiJoinEstimate = filterByEquiJoinClauses(crossJoinStats, node.getCriteria(), session);
if (equiJoinEstimate.isOutputRowCountUnknown()) {
return PlanNodeStatsEstimate.unknown();
}
if (node.getFilter().isEmpty()) {
return equiJoinEstimate;
}
PlanNodeStatsEstimate filteredEquiJoinEstimate = filterStatsCalculator.filterStats(equiJoinEstimate, node.getFilter().get(), session);
if (filteredEquiJoinEstimate.isOutputRowCountUnknown()) {
return normalizer.normalize(equiJoinEstimate.mapOutputRowCount(rowCount -> rowCount * UNKNOWN_FILTER_COEFFICIENT));
}
return filteredEquiJoinEstimate;
}
private PlanNodeStatsEstimate filterByEquiJoinClauses(
PlanNodeStatsEstimate stats,
Collection clauses,
Session session)
{
checkArgument(!clauses.isEmpty(), "clauses is empty");
// Join equality clauses are usually correlated. Therefore, we shouldn't treat each join equality
// clause separately because stats estimates would be way off.
List knownEstimates = clauses.stream()
.map(clause -> {
Comparison predicate = new Comparison(EQUAL, clause.getLeft().toSymbolReference(), clause.getRight().toSymbolReference());
return new PlanNodeStatsEstimateWithClause(filterStatsCalculator.filterStats(stats, predicate, session), clause);
})
.collect(toImmutableList());
double outputRowCount = estimateCorrelatedConjunctionRowCount(
stats,
knownEstimates.stream().map(PlanNodeStatsEstimateWithClause::getEstimate).collect(toImmutableList()),
getJoinMultiClauseIndependenceFactor(session));
if (isNaN(outputRowCount)) {
return PlanNodeStatsEstimate.unknown();
}
return normalizer.normalize(new PlanNodeStatsEstimate(outputRowCount, intersectCorrelatedJoinClause(stats, knownEstimates)));
}
private static Map intersectCorrelatedJoinClause(
PlanNodeStatsEstimate stats,
List equiJoinClauseEstimates)
{
// Add initial statistics (including stats for columns which are not part of equi-join clauses)
PlanNodeStatsEstimate.Builder result = PlanNodeStatsEstimate.builder()
.addSymbolStatistics(stats.getSymbolStatistics());
for (PlanNodeStatsEstimateWithClause estimateWithClause : equiJoinClauseEstimates) {
EquiJoinClause clause = estimateWithClause.getClause();
// we just clear null fraction and adjust ranges here, selectivity is handled outside this function
SymbolStatsEstimate leftStats = stats.getSymbolStatistics(clause.getLeft());
SymbolStatsEstimate rightStats = stats.getSymbolStatistics(clause.getRight());
StatisticRange leftRange = StatisticRange.from(leftStats);
StatisticRange rightRange = StatisticRange.from(rightStats);
StatisticRange intersect = leftRange.intersect(rightRange);
double leftFilterValue = firstNonNaN(leftRange.overlapPercentWith(intersect), 1);
double rightFilterValue = firstNonNaN(rightRange.overlapPercentWith(intersect), 1);
double leftNdvInRange = leftFilterValue * leftRange.getDistinctValuesCount();
double rightNdvInRange = rightFilterValue * rightRange.getDistinctValuesCount();
double retainedNdv = MoreMath.min(leftNdvInRange, rightNdvInRange);
SymbolStatsEstimate newLeftStats = buildFrom(leftStats)
.setNullsFraction(0)
.setStatisticsRange(intersect)
.setDistinctValuesCount(retainedNdv)
.build();
SymbolStatsEstimate newRightStats = buildFrom(rightStats)
.setNullsFraction(0)
.setStatisticsRange(intersect)
.setDistinctValuesCount(retainedNdv)
.build();
result.addSymbolStatistics(clause.getLeft(), newLeftStats)
.addSymbolStatistics(clause.getRight(), newRightStats);
}
return result.build().getSymbolStatistics();
}
/**
* Calculates statistics for unmatched left rows.
*/
@VisibleForTesting
PlanNodeStatsEstimate calculateJoinComplementStats(
Optional filter,
List criteria,
PlanNodeStatsEstimate leftStats,
PlanNodeStatsEstimate rightStats)
{
if (rightStats.getOutputRowCount() == 0) {
// no left side rows are matched
return leftStats;
}
if (criteria.isEmpty()) {
// TODO: account for non-equi conditions
if (filter.isPresent()) {
return PlanNodeStatsEstimate.unknown();
}
return normalizer.normalize(leftStats.mapOutputRowCount(rowCount -> 0.0));
}
// TODO: add support for non-equality conditions (e.g: <=, !=, >)
int numberOfFilterClauses = filter.map(expression -> extractConjuncts(expression).size()).orElse(0);
// Heuristics: select the most selective criteria for join complement clause.
// Principals behind this heuristics is the same as in computeInnerJoinStats:
// select "driving join clause" that reduces matched rows the most.
return criteria.stream()
.map(drivingClause -> calculateJoinComplementStats(leftStats, rightStats, drivingClause, criteria.size() - 1 + numberOfFilterClauses))
.filter(estimate -> !estimate.isOutputRowCountUnknown())
.max(comparingDouble(PlanNodeStatsEstimate::getOutputRowCount))
.map(normalizer::normalize)
.orElse(PlanNodeStatsEstimate.unknown());
}
private PlanNodeStatsEstimate calculateJoinComplementStats(
PlanNodeStatsEstimate leftStats,
PlanNodeStatsEstimate rightStats,
EquiJoinClause drivingClause,
int numberOfRemainingClauses)
{
PlanNodeStatsEstimate result = leftStats;
SymbolStatsEstimate leftColumnStats = leftStats.getSymbolStatistics(drivingClause.getLeft());
SymbolStatsEstimate rightColumnStats = rightStats.getSymbolStatistics(drivingClause.getRight());
// TODO: use range methods when they have defined (and consistent) semantics
double leftNDV = leftColumnStats.getDistinctValuesCount();
double matchingRightNDV = rightColumnStats.getDistinctValuesCount() * unmatchedJoinComplementNdvsCoefficient;
if (leftNDV > matchingRightNDV) {
// Assume "excessive" left NDVs and left null rows are unmatched.
double nonMatchingLeftValuesFraction = leftColumnStats.getValuesFraction() * (leftNDV - matchingRightNDV) / leftNDV;
double scaleFactor = nonMatchingLeftValuesFraction + leftColumnStats.getNullsFraction();
double newLeftNullsFraction = leftColumnStats.getNullsFraction() / scaleFactor;
result = result.mapSymbolColumnStatistics(drivingClause.getLeft(), columnStats ->
SymbolStatsEstimate.buildFrom(columnStats)
.setLowValue(leftColumnStats.getLowValue())
.setHighValue(leftColumnStats.getHighValue())
.setNullsFraction(newLeftNullsFraction)
.setDistinctValuesCount(leftNDV - matchingRightNDV)
.build());
result = result.mapOutputRowCount(rowCount -> rowCount * scaleFactor);
}
else if (leftNDV <= matchingRightNDV) {
// Assume all non-null left rows are matched. Therefore only null left rows are unmatched.
result = result.mapSymbolColumnStatistics(drivingClause.getLeft(), columnStats ->
SymbolStatsEstimate.buildFrom(columnStats)
.setLowValue(NaN)
.setHighValue(NaN)
.setNullsFraction(1.0)
.setDistinctValuesCount(0.0)
.build());
result = result.mapOutputRowCount(rowCount -> rowCount * leftColumnStats.getNullsFraction());
}
else {
// either leftNDV or rightNDV is NaN
return PlanNodeStatsEstimate.unknown();
}
// limit the number of complement rows (to left row count) and account for remaining clauses
result = result.mapOutputRowCount(rowCount -> min(leftStats.getOutputRowCount(), rowCount / Math.pow(UNKNOWN_FILTER_COEFFICIENT, numberOfRemainingClauses)));
return result;
}
@VisibleForTesting
PlanNodeStatsEstimate addJoinComplementStats(
PlanNodeStatsEstimate sourceStats,
PlanNodeStatsEstimate innerJoinStats,
PlanNodeStatsEstimate joinComplementStats)
{
double innerJoinRowCount = innerJoinStats.getOutputRowCount();
double joinComplementRowCount = joinComplementStats.getOutputRowCount();
if (joinComplementRowCount == 0) {
return innerJoinStats;
}
double outputRowCount = innerJoinRowCount + joinComplementRowCount;
PlanNodeStatsEstimate.Builder outputStats = PlanNodeStatsEstimate.buildFrom(innerJoinStats);
outputStats.setOutputRowCount(outputRowCount);
for (Symbol symbol : joinComplementStats.getSymbolsWithKnownStatistics()) {
SymbolStatsEstimate leftSymbolStats = sourceStats.getSymbolStatistics(symbol);
SymbolStatsEstimate innerJoinSymbolStats = innerJoinStats.getSymbolStatistics(symbol);
SymbolStatsEstimate joinComplementSymbolStats = joinComplementStats.getSymbolStatistics(symbol);
// weighted average
double newNullsFraction = (innerJoinSymbolStats.getNullsFraction() * innerJoinRowCount + joinComplementSymbolStats.getNullsFraction() * joinComplementRowCount) / outputRowCount;
outputStats.addSymbolStatistics(symbol, SymbolStatsEstimate.buildFrom(innerJoinSymbolStats)
// in outer join low value, high value and NDVs of outer side columns are preserved
.setLowValue(leftSymbolStats.getLowValue())
.setHighValue(leftSymbolStats.getHighValue())
.setDistinctValuesCount(leftSymbolStats.getDistinctValuesCount())
.setNullsFraction(newNullsFraction)
.build());
}
// add nulls to columns that don't exist in right stats
for (Symbol symbol : difference(innerJoinStats.getSymbolsWithKnownStatistics(), joinComplementStats.getSymbolsWithKnownStatistics())) {
SymbolStatsEstimate innerJoinSymbolStats = innerJoinStats.getSymbolStatistics(symbol);
double newNullsFraction = (innerJoinSymbolStats.getNullsFraction() * innerJoinRowCount + joinComplementRowCount) / outputRowCount;
outputStats.addSymbolStatistics(symbol, innerJoinSymbolStats.mapNullsFraction(nullsFraction -> newNullsFraction));
}
return outputStats.build();
}
private PlanNodeStatsEstimate crossJoinStats(JoinNode node, PlanNodeStatsEstimate leftStats, PlanNodeStatsEstimate rightStats)
{
PlanNodeStatsEstimate.Builder builder = PlanNodeStatsEstimate.builder()
.setOutputRowCount(leftStats.getOutputRowCount() * rightStats.getOutputRowCount());
node.getLeft().getOutputSymbols().forEach(symbol -> builder.addSymbolStatistics(symbol, leftStats.getSymbolStatistics(symbol)));
node.getRight().getOutputSymbols().forEach(symbol -> builder.addSymbolStatistics(symbol, rightStats.getSymbolStatistics(symbol)));
return normalizer.normalize(builder.build());
}
private List flippedCriteria(JoinNode node)
{
return node.getCriteria().stream()
.map(EquiJoinClause::flip)
.collect(toImmutableList());
}
private static class PlanNodeStatsEstimateWithClause
{
private final PlanNodeStatsEstimate estimate;
private final EquiJoinClause clause;
private PlanNodeStatsEstimateWithClause(PlanNodeStatsEstimate estimate, EquiJoinClause clause)
{
this.estimate = requireNonNull(estimate, "estimate is null");
this.clause = requireNonNull(clause, "clause is null");
}
private PlanNodeStatsEstimate getEstimate()
{
return estimate;
}
private EquiJoinClause getClause()
{
return clause;
}
}
}
