com.facebook.presto.sql.planner.iterative.rule.PruneAggregationColumns.java Source code

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Here is the source code for com.facebook.presto.sql.planner.iterative.rule.PruneAggregationColumns.java

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/*
 * 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 com.facebook.presto.sql.planner.iterative.rule;

import com.facebook.presto.sql.planner.PlanNodeIdAllocator;
import com.facebook.presto.sql.planner.Symbol;
import com.facebook.presto.sql.planner.plan.AggregationNode;
import com.facebook.presto.sql.planner.plan.PlanNode;
import com.google.common.collect.Maps;

import java.util.Map;
import java.util.Optional;
import java.util.Set;

import static com.facebook.presto.sql.planner.plan.Patterns.aggregation;

public class PruneAggregationColumns extends ProjectOffPushDownRule<AggregationNode> {
    public PruneAggregationColumns() {
        super(aggregation());
    }

    @Override
    protected Optional<PlanNode> pushDownProjectOff(PlanNodeIdAllocator idAllocator,
            AggregationNode aggregationNode, Set<Symbol> referencedOutputs) {
        Map<Symbol, AggregationNode.Aggregation> prunedAggregations = Maps
                .filterKeys(aggregationNode.getAggregations(), referencedOutputs::contains);

        if (prunedAggregations.size() == aggregationNode.getAggregations().size()) {
            return Optional.empty();
        }

        // PruneAggregationSourceColumns will subsequently project off any newly unused inputs.
        return Optional.of(new AggregationNode(aggregationNode.getId(), aggregationNode.getSource(),
                prunedAggregations, aggregationNode.getGroupingSets(), aggregationNode.getStep(),
                aggregationNode.getHashSymbol(), aggregationNode.getGroupIdSymbol()));
    }
}