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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.
*/
#include <algorithm> // std::sort
#include <cmath> // std::pow
#include <functional> // std::greater
#include "mongo/db/query/optimizer/utils/ce_math.h"
namespace mongo::ce {
bool validSelectivity(SelectivityType sel) {
return (sel >= 0.0 && sel <= 1.0);
}
bool validCardinality(CEType card) {
return (card >= kMinCard && card <= std::numeric_limits<CEType>::max());
}
SelectivityType conjExponentialBackoff(std::vector<SelectivityType> conjSelectivities) {
size_t actualMaxBackoffElements = std::min(conjSelectivities.size(), kMaxBackoffElements);
std::partial_sort(conjSelectivities.begin(),
conjSelectivities.begin() + actualMaxBackoffElements,
conjSelectivities.end());
SelectivityType sel = conjSelectivities[0];
SelectivityType f = 1.0;
size_t i = 1;
while (i < actualMaxBackoffElements) {
f /= 2.0;
sel *= std::pow(conjSelectivities[i], f);
i++;
}
return sel;
}
SelectivityType disjExponentialBackoff(std::vector<SelectivityType> disjSelectivities) {
size_t actualMaxBackoffElements = std::min(disjSelectivities.size(), kMaxBackoffElements);
std::partial_sort(disjSelectivities.begin(),
disjSelectivities.begin() + actualMaxBackoffElements,
disjSelectivities.end(),
std::greater<SelectivityType>());
SelectivityType sel = 1.0 - disjSelectivities[0];
SelectivityType f = 1.0;
size_t i = 1;
while (i < actualMaxBackoffElements) {
f /= 2.0;
sel *= std::pow(1 - disjSelectivities[i], f);
i++;
}
return 1.0 - sel;
}
} // namespace mongo::ce
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