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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/ce/array_histogram.h"
#include "mongo/db/query/optimizer/defs.h"
#include "mongo/db/query/optimizer/index_bounds.h"
namespace mongo::ce {
constexpr double kInvalidEstimate = -1.0;
enum class EstimationType { kEqual, kLess, kLessOrEqual, kGreater, kGreaterOrEqual };
enum class EstimationAlgo { HistogramV1, HistogramV2, HistogramV3 };
const stdx::unordered_map<EstimationType, std::string> estimationTypeName = {
{EstimationType::kEqual, "eq"},
{EstimationType::kLess, "lt"},
{EstimationType::kLessOrEqual, "lte"},
{EstimationType::kGreater, "gt"},
{EstimationType::kGreaterOrEqual, "gte"}};
struct EstimationResult {
double card;
double ndv;
EstimationResult operator-(const EstimationResult& other) const {
return {card - other.card, ndv - other.ndv};
}
};
/**
* Returns cumulative total statistics for a histogram.
*/
EstimationResult getTotals(const ScalarHistogram& h);
/**
* Compute an estimate for a given value and estimation type. Use linear interpolation for values
* that fall inside of histogram buckets.
*/
EstimationResult estimate(const ScalarHistogram& h,
sbe::value::TypeTags tag,
sbe::value::Value val,
EstimationType type);
/**
* Given an array histogram, an interval, and the input cardinality, estimates the cardinality of
* the interval.
*/
double estimateIntervalCardinality(const ArrayHistogram& estimator,
const optimizer::IntervalRequirement& interval,
optimizer::CEType inputCardinality,
bool includeScalar);
/**
* Estimates the cardinality of an equality predicate given an ArrayHistogram and an SBE value and
* type tag pair.
*/
double estimateCardEq(const ArrayHistogram& ah,
sbe::value::TypeTags tag,
sbe::value::Value val,
bool includeScalar);
/**
* Estimates the cardinality of a range predicate given an ArrayHistogram and a range predicate.
* Set 'includeScalar' to true to indicate whether or not the provided range should include no-array
* values. The other fields define the range of the estimation.
*/
double estimateCardRange(const ArrayHistogram& ah,
bool lowInclusive,
sbe::value::TypeTags tagLow,
sbe::value::Value valLow,
bool highInclusive,
sbe::value::TypeTags tagHigh,
sbe::value::Value valHigh,
bool includeScalar,
EstimationAlgo estAlgo = EstimationAlgo::HistogramV2);
} // namespace mongo::ce
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