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/**
* Copyright (C) 2022-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include "mongo/db/query/optimizer/cascades/interfaces.h"
#include "mongo/db/query/stats/collection_statistics.h"
namespace mongo::optimizer::ce {
enum IntervalEstimationMode { kUseHistogram, kUseTypeCounts, kFallback };
using IntervalEstimation =
std::tuple<IntervalEstimationMode,
boost::optional<std::reference_wrapper<const BoundRequirement>>,
boost::optional<std::reference_wrapper<const BoundRequirement>>>;
/**
* Analyzes an interval to define an estimation mode and summarize the bounds. This method is in the
* header for unit tests to use.
*/
IntervalEstimation analyzeIntervalEstimationMode(const stats::ArrayHistogram* histogram,
const IntervalRequirement& interval);
class HistogramTransport;
class HistogramEstimator : public cascades::CardinalityEstimator {
public:
HistogramEstimator(std::shared_ptr<stats::CollectionStatistics> stats,
std::unique_ptr<cascades::CardinalityEstimator> fallbackCE);
~HistogramEstimator();
CEType deriveCE(const Metadata& metadata,
const cascades::Memo& memo,
const properties::LogicalProps& logicalProps,
ABT::reference_type logicalNodeRef) const final;
private:
std::unique_ptr<HistogramTransport> _transport;
};
} // namespace mongo::optimizer::ce
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