BuildAggForUnion.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.plans.algebra.SetOperation.Qualifier;
import org.apache.doris.nereids.trees.plans.logical.LogicalAggregate;

import com.google.common.collect.ImmutableList;

import java.util.Optional;

/**
 * Convert Union into Agg + UnionAll.
 * <pre>
 *             Agg
 * Union ->     |
 *           UnionAll
 * </pre>
 */
public class BuildAggForUnion extends OneRewriteRuleFactory {
    @Override
    public Rule build() {
        return logicalUnion().when(union -> union.getQualifier() == Qualifier.DISTINCT)
                .then(union -> new LogicalAggregate<>(ImmutableList.copyOf(union.getOutputs()), union.getOutputs(),
                        true, Optional.empty(), union.withAllQualifier()))
                .toRule(RuleType.BUILD_AGG_FOR_UNION);
    }
}