PushDownJoinOtherCondition.java

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package org.apache.doris.nereids.rules.rewrite;

import org.apache.doris.nereids.rules.Rule;
import org.apache.doris.nereids.rules.RuleType;
import org.apache.doris.nereids.trees.expressions.Expression;
import org.apache.doris.nereids.trees.expressions.Slot;
import org.apache.doris.nereids.trees.expressions.literal.BooleanLiteral;
import org.apache.doris.nereids.trees.plans.JoinType;
import org.apache.doris.nereids.trees.plans.Plan;
import org.apache.doris.nereids.trees.plans.logical.LogicalJoin;
import org.apache.doris.nereids.util.PlanUtils;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import com.google.common.collect.Sets;

import java.util.List;
import java.util.Set;

/**
 * Push the other join conditions in LogicalJoin to children.
 */
public class PushDownJoinOtherCondition extends OneRewriteRuleFactory {
    private static final ImmutableList<JoinType> PUSH_DOWN_LEFT_VALID_TYPE = ImmutableList.of(
            JoinType.INNER_JOIN,
            JoinType.LEFT_SEMI_JOIN,
            JoinType.RIGHT_OUTER_JOIN,
            JoinType.RIGHT_ANTI_JOIN,
            JoinType.RIGHT_SEMI_JOIN,
            JoinType.CROSS_JOIN
    );

    private static final ImmutableList<JoinType> PUSH_DOWN_RIGHT_VALID_TYPE = ImmutableList.of(
            JoinType.INNER_JOIN,
            JoinType.LEFT_OUTER_JOIN,
            JoinType.LEFT_ANTI_JOIN,
            JoinType.NULL_AWARE_LEFT_ANTI_JOIN,
            JoinType.LEFT_SEMI_JOIN,
            JoinType.RIGHT_SEMI_JOIN,
            JoinType.CROSS_JOIN
    );

    @Override
    public Rule build() {
        return logicalJoin()
                // TODO: we may need another rule to handle on true or on false condition
                .when(join -> !join.getOtherJoinConjuncts().isEmpty() && !(join.getOtherJoinConjuncts().size() == 1
                        && join.getOtherJoinConjuncts().get(0) instanceof BooleanLiteral)
                        && !join.isMarkJoin())
                .then(join -> {
                    List<Expression> otherJoinConjuncts = join.getOtherJoinConjuncts();
                    List<Expression> remainingOther = Lists.newArrayList();
                    Set<Expression> leftConjuncts = Sets.newHashSet();
                    Set<Expression> rightConjuncts = Sets.newHashSet();

                    for (Expression otherConjunct : otherJoinConjuncts) {
                        if (PUSH_DOWN_LEFT_VALID_TYPE.contains(join.getJoinType())
                                && allCoveredBy(otherConjunct, join.left().getOutputSet())) {
                            leftConjuncts.add(otherConjunct);
                        } else if (PUSH_DOWN_RIGHT_VALID_TYPE.contains(join.getJoinType())
                                && allCoveredBy(otherConjunct, join.right().getOutputSet())) {
                            rightConjuncts.add(otherConjunct);
                        } else {
                            remainingOther.add(otherConjunct);
                        }
                    }

                    if (leftConjuncts.isEmpty() && rightConjuncts.isEmpty()) {
                        return null;
                    }

                    Plan left = PlanUtils.filterOrSelf(leftConjuncts, join.left());
                    Plan right = PlanUtils.filterOrSelf(rightConjuncts, join.right());

                    return new LogicalJoin<>(join.getJoinType(), join.getHashJoinConjuncts(),
                            remainingOther, join.getMarkJoinConjuncts(), join.getDistributeHint(),
                            join.getMarkJoinSlotReference(), left, right, join.getJoinReorderContext());

                }).toRule(RuleType.PUSH_DOWN_JOIN_OTHER_CONDITION);
    }

    private boolean allCoveredBy(Expression predicate, Set<Slot> inputSlotSet) {
        return inputSlotSet.containsAll(predicate.getInputSlots());
    }
}