io.prestosql.sql.planner.iterative.rule.PruneWindowColumns.java Source code

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Here is the source code for io.prestosql.sql.planner.iterative.rule.PruneWindowColumns.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 io.prestosql.sql.planner.iterative.rule;

import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Maps;
import io.prestosql.sql.planner.PlanNodeIdAllocator;
import io.prestosql.sql.planner.Symbol;
import io.prestosql.sql.planner.SymbolsExtractor;
import io.prestosql.sql.planner.plan.PlanNode;
import io.prestosql.sql.planner.plan.WindowNode;

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

import static io.prestosql.sql.planner.iterative.rule.Util.restrictOutputs;
import static io.prestosql.sql.planner.plan.Patterns.window;

public class PruneWindowColumns extends ProjectOffPushDownRule<WindowNode> {
    public PruneWindowColumns() {
        super(window());
    }

    @Override
    protected Optional<PlanNode> pushDownProjectOff(PlanNodeIdAllocator idAllocator, WindowNode windowNode,
            Set<Symbol> referencedOutputs) {
        Map<Symbol, WindowNode.Function> referencedFunctions = Maps.filterKeys(windowNode.getWindowFunctions(),
                referencedOutputs::contains);

        if (referencedFunctions.isEmpty()) {
            return Optional.of(windowNode.getSource());
        }

        ImmutableSet.Builder<Symbol> referencedInputs = ImmutableSet.<Symbol>builder().addAll(
                windowNode.getSource().getOutputSymbols().stream().filter(referencedOutputs::contains).iterator())
                .addAll(windowNode.getPartitionBy());

        windowNode.getOrderingScheme()
                .ifPresent(orderingScheme -> orderingScheme.getOrderBy().forEach(referencedInputs::add));
        windowNode.getHashSymbol().ifPresent(referencedInputs::add);

        for (WindowNode.Function windowFunction : referencedFunctions.values()) {
            referencedInputs.addAll(SymbolsExtractor.extractUnique(windowFunction.getFunctionCall()));
            windowFunction.getFrame().getStartValue().ifPresent(referencedInputs::add);
            windowFunction.getFrame().getEndValue().ifPresent(referencedInputs::add);
        }

        PlanNode prunedWindowNode = new WindowNode(windowNode.getId(),
                restrictOutputs(idAllocator, windowNode.getSource(), referencedInputs.build())
                        .orElse(windowNode.getSource()),
                windowNode.getSpecification(), referencedFunctions, windowNode.getHashSymbol(),
                windowNode.getPrePartitionedInputs(), windowNode.getPreSortedOrderPrefix());

        if (prunedWindowNode.getOutputSymbols().size() == windowNode.getOutputSymbols().size()) {
            // Neither function pruning nor input pruning was successful.
            return Optional.empty();
        }

        return Optional.of(prunedWindowNode);
    }
}