ConvertOuterJoinToAntiJoin.java
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package org.apache.doris.nereids.rules.rewrite;
import org.apache.doris.nereids.jobs.JobContext;
import org.apache.doris.nereids.trees.expressions.Alias;
import org.apache.doris.nereids.trees.expressions.ComparisonPredicate;
import org.apache.doris.nereids.trees.expressions.ExprId;
import org.apache.doris.nereids.trees.expressions.Expression;
import org.apache.doris.nereids.trees.expressions.NamedExpression;
import org.apache.doris.nereids.trees.expressions.NullSafeEqual;
import org.apache.doris.nereids.trees.expressions.Slot;
import org.apache.doris.nereids.trees.expressions.literal.NullLiteral;
import org.apache.doris.nereids.trees.plans.JoinType;
import org.apache.doris.nereids.trees.plans.Plan;
import org.apache.doris.nereids.trees.plans.logical.LogicalFilter;
import org.apache.doris.nereids.trees.plans.logical.LogicalJoin;
import org.apache.doris.nereids.trees.plans.logical.LogicalProject;
import org.apache.doris.nereids.trees.plans.visitor.CustomRewriter;
import org.apache.doris.nereids.trees.plans.visitor.DefaultPlanRewriter;
import org.apache.doris.nereids.util.TypeUtils;
import com.google.common.collect.ImmutableList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.stream.Collectors;
/**
* project(A.*)
* - filter(B.slot is null)
* - LeftOuterJoin(A, B)
* ==============================>
* project(A.*)
* - LeftAntiJoin(A, B)
*/
public class ConvertOuterJoinToAntiJoin extends DefaultPlanRewriter<Map<ExprId, ExprId>> implements CustomRewriter {
private ExprIdRewriter exprIdReplacer;
@Override
public Plan rewriteRoot(Plan plan, JobContext jobContext) {
if (!plan.containsType(LogicalJoin.class)) {
return plan;
}
Map<ExprId, ExprId> replaceMap = new HashMap<>();
ExprIdRewriter.ReplaceRule replaceRule = new ExprIdRewriter.ReplaceRule(replaceMap);
exprIdReplacer = new ExprIdRewriter(replaceRule, jobContext);
return plan.accept(this, replaceMap);
}
@Override
public Plan visit(Plan plan, Map<ExprId, ExprId> replaceMap) {
plan = visitChildren(this, plan, replaceMap);
plan = exprIdReplacer.rewriteExpr(plan, replaceMap);
return plan;
}
@Override
public Plan visitLogicalFilter(LogicalFilter<? extends Plan> filter, Map<ExprId, ExprId> replaceMap) {
filter = (LogicalFilter<? extends Plan>) visit(filter, replaceMap);
if (!(filter.child() instanceof LogicalJoin)) {
return filter;
}
return toAntiJoin((LogicalFilter<LogicalJoin<Plan, Plan>>) filter, replaceMap);
}
private Plan toAntiJoin(LogicalFilter<LogicalJoin<Plan, Plan>> filter, Map<ExprId, ExprId> replaceMap) {
LogicalJoin<Plan, Plan> join = filter.child();
if (join.getJoinType().isAsofJoin()
|| (!join.getJoinType().isLeftOuterJoin() && !join.getJoinType().isRightOuterJoin())) {
return filter;
}
Set<Slot> alwaysNullSlots = filter.getConjuncts().stream()
.filter(p -> TypeUtils.isNull(p).isPresent())
.flatMap(p -> p.getInputSlots().stream())
.collect(Collectors.toSet());
Set<Slot> nullRejectedJoinSlots = getNullRejectedJoinSlots(join);
List<Slot> leftOutput = join.left().getOutput();
List<Slot> rightOutput = join.right().getOutput();
List<Slot> joinOutput = join.getOutput();
Set<Slot> leftAlwaysNullSlots = getAlwaysNullSlots(leftOutput,
joinOutput.subList(0, leftOutput.size()), alwaysNullSlots, nullRejectedJoinSlots);
Set<Slot> rightAlwaysNullSlots = getAlwaysNullSlots(rightOutput,
joinOutput.subList(leftOutput.size(), leftOutput.size() + rightOutput.size()),
alwaysNullSlots, nullRejectedJoinSlots);
Plan newChild = null;
if (join.getJoinType().isLeftOuterJoin() && !rightAlwaysNullSlots.isEmpty()) {
newChild = join.withJoinTypeAndContext(JoinType.LEFT_ANTI_JOIN, join.getJoinReorderContext());
}
if (join.getJoinType().isRightOuterJoin() && !leftAlwaysNullSlots.isEmpty()) {
newChild = join.withJoinTypeAndContext(JoinType.RIGHT_ANTI_JOIN, join.getJoinReorderContext());
}
if (newChild == null) {
return filter;
}
if (!newChild.getOutputSet().containsAll(filter.getInputSlots())) {
// if there are slots that don't belong to join output, we use null alias to replace them
// such as:
// project(A.id, null as B.id)
// - (A left anti join B)
Set<Slot> joinOutputs = newChild.getOutputSet();
ImmutableList.Builder<NamedExpression> projectsBuilder = ImmutableList.builder();
for (NamedExpression e : filter.getOutput()) {
if (joinOutputs.contains(e)) {
projectsBuilder.add(e);
} else {
Alias newAlias = new Alias(new NullLiteral(e.getDataType()), e.getName(), e.getQualifier());
replaceMap.put(e.getExprId(), newAlias.getExprId());
projectsBuilder.add(newAlias);
}
}
newChild = new LogicalProject<>(projectsBuilder.build(), newChild);
return exprIdReplacer.rewriteExpr(filter.withChildren(newChild), replaceMap);
} else {
return filter.withChildren(newChild);
}
}
private Set<Slot> getNullRejectedJoinSlots(LogicalJoin<Plan, Plan> join) {
Set<Slot> leftOutputSet = join.left().getOutputSet();
Set<Slot> rightOutputSet = join.right().getOutputSet();
Set<Slot> nullRejectedJoinSlots = new HashSet<>();
collectNullRejectedJoinSlots(join.getHashJoinConjuncts(), leftOutputSet, rightOutputSet,
nullRejectedJoinSlots);
collectNullRejectedJoinSlots(join.getOtherJoinConjuncts(), leftOutputSet, rightOutputSet,
nullRejectedJoinSlots);
return nullRejectedJoinSlots;
}
private void collectNullRejectedJoinSlots(List<Expression> conjuncts, Set<Slot> leftOutputSet,
Set<Slot> rightOutputSet, Set<Slot> nullRejectedJoinSlots) {
for (Expression conjunct : conjuncts) {
if (!(conjunct instanceof ComparisonPredicate) || conjunct instanceof NullSafeEqual) {
continue;
}
ComparisonPredicate predicate = (ComparisonPredicate) conjunct;
if (isSlotComparisonBetweenChildren(predicate, leftOutputSet, rightOutputSet)) {
nullRejectedJoinSlots.addAll(predicate.getInputSlots());
}
}
}
private Set<Slot> getAlwaysNullSlots(List<Slot> childOutput, List<Slot> joinOutput, Set<Slot> alwaysNullSlots,
Set<Slot> nullRejectedJoinSlots) {
Set<Slot> result = new HashSet<>();
for (int i = 0; i < childOutput.size(); i++) {
Slot childSlot = childOutput.get(i);
Slot outputSlot = joinOutput.get(i);
if ((alwaysNullSlots.contains(childSlot) || alwaysNullSlots.contains(outputSlot))
&& (!childSlot.nullable() || nullRejectedJoinSlots.contains(childSlot))) {
result.add(childSlot);
}
}
return result;
}
private boolean isSlotComparisonBetweenChildren(ComparisonPredicate predicate, Set<Slot> leftOutputSet,
Set<Slot> rightOutputSet) {
Expression left = predicate.left();
Expression right = predicate.right();
if (!(left instanceof Slot) || !(right instanceof Slot)) {
return false;
}
return (leftOutputSet.contains(left) && rightOutputSet.contains(right))
|| (leftOutputSet.contains(right) && rightOutputSet.contains(left));
}
}