InferAggNotNull.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.Not;
import org.apache.doris.nereids.trees.expressions.functions.agg.AggregateFunction;
import org.apache.doris.nereids.trees.expressions.functions.agg.Avg;
import org.apache.doris.nereids.trees.expressions.functions.agg.Count;
import org.apache.doris.nereids.trees.expressions.functions.agg.Max;
import org.apache.doris.nereids.trees.expressions.functions.agg.Min;
import org.apache.doris.nereids.trees.expressions.functions.agg.Sum;
import org.apache.doris.nereids.trees.plans.Plan;
import org.apache.doris.nereids.trees.plans.algebra.Filter;
import org.apache.doris.nereids.trees.plans.logical.LogicalAggregate;
import org.apache.doris.nereids.util.ExpressionUtils;
import org.apache.doris.nereids.util.PlanUtils;

import com.google.common.collect.ImmutableSet;

import java.util.Collections;
import java.util.Set;
import java.util.stream.Collectors;

/**
 * InferNotNull from Agg count(distinct);
 */
public class InferAggNotNull extends OneRewriteRuleFactory {
    @Override
    public Rule build() {
        return logicalAggregate()
                .when(agg -> agg.getGroupByExpressions().size() == 0)
                .when(agg -> agg.getAggregateFunctions().size() == 1)
                .when(agg -> {
                    Set<AggregateFunction> funcs = agg.getAggregateFunctions();
                    return funcs.stream().allMatch(f -> f instanceof Count)
                            || funcs.stream().allMatch(f -> f instanceof Avg)
                            || funcs.stream().allMatch(f -> f instanceof Sum)
                            || funcs.stream().allMatch(f -> f instanceof Max)
                            || funcs.stream().allMatch(f -> f instanceof Min);
                }).thenApply(ctx -> {
                    LogicalAggregate<Plan> agg = ctx.root;
                    Set<Expression> exprs = agg.getAggregateFunctions().stream().flatMap(f -> f.children().stream())
                            .collect(Collectors.toSet());
                    Set<Expression> isNotNulls = ExpressionUtils.inferNotNull(exprs, ctx.cascadesContext);
                    Set<Expression> predicates = Collections.emptySet();
                    if ((agg.child() instanceof Filter)) {
                        predicates = ((Filter) agg.child()).getConjuncts();
                    }
                    ImmutableSet.Builder<Expression> needGenerateNotNullsBuilder = ImmutableSet.builder();
                    for (Expression isNotNull : isNotNulls) {
                        if (!predicates.contains(isNotNull)) {
                            isNotNull = ((Not) isNotNull).withGeneratedIsNotNull(true);
                            if (!predicates.contains(isNotNull)) {
                                needGenerateNotNullsBuilder.add(isNotNull);
                            }
                        }
                    }
                    Set<Expression> needGenerateNotNulls = needGenerateNotNullsBuilder.build();
                    if (needGenerateNotNulls.isEmpty()) {
                        return null;
                    }
                    return agg.withChildren(PlanUtils.filter(needGenerateNotNulls, agg.child()).get());
                }).toRule(RuleType.INFER_AGG_NOT_NULL);
    }
}