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/**
* Copyright (C) 2023-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 "mongo/db/query/optimizer/utils/ce_math.h"
#include "mongo/db/query/optimizer/utils/memo_utils.h"
namespace mongo::optimizer::ce {
constexpr SelectivityType kDefaultFilterSel{0.1};
constexpr SelectivityType kDefaultExistsSel{0.70};
// The selectivities used in the piece-wise function for open-range intervals.
// Note that we assume a smaller input cardinality will result in a less selective range.
constexpr SelectivityType kSmallCardOpenRangeSel{0.70};
constexpr SelectivityType kMediumCardOpenRangeSel{0.45};
constexpr SelectivityType kLargeCardOpenRangeSel{0.33};
// The selectivities used in the piece-wise function for closed-range intervals.
// Note that we assume a smaller input cardinality will result in a less selective range.
constexpr SelectivityType kSmallCardClosedRangeSel{0.50};
constexpr SelectivityType kMediumCardClosedRangeSel{0.33};
constexpr SelectivityType kLargeCardClosedRangeSel{0.20};
// Global and Local selectivity should multiply to the Complete selectivity.
constexpr SelectivityType kDefaultCompleteGroupSel{0.01};
constexpr SelectivityType kDefaultLocalGroupSel{0.02};
constexpr SelectivityType kDefaultGlobalGroupSel{0.5};
// Since there are only two boolean values, when we have a count of arrays containing booleans, we
// estimate the default selectivity of booleans in arrays as 1/2.
constexpr double kDefaultArrayBoolSel{0.5};
// The following constants are the steps used in the piece-wise functions that select selectivies
// based on input cardinality.
constexpr CEType kSmallLimit{20.0};
constexpr CEType kMediumLimit{100.0};
// Assumed average number of elements in an array. This is a unitless constant.
constexpr double kDefaultAverageArraySize{10.0};
/**
* Returns the heuristic selectivity of equalities. To avoid super small selectivities for small
* cardinalities, that would result in 0 cardinality for many small inputs, the estimate is scaled
* as inputCard grows. The bigger inputCard, the smaller the selectivity.
*/
SelectivityType heuristicEqualitySel(CEType inputCard);
/**
* Returns the heuristic selectivity of intervals with bounds on both ends. These intervals are
* considered less selective than equalities.
* Examples: (a > 'abc' AND a < 'hta'), (0 < b <= 13)
*/
SelectivityType heuristicClosedRangeSel(CEType inputCard);
/**
* Returns the heuristic selectivity of intervals open on one end. These intervals are considered
* less selective than those with both ends specified by the user query.
* Examples: (a > 'xyz'), (b <= 13)
*/
SelectivityType heuristicOpenRangeSel(CEType inputCard);
/**
* Returns the heuristic selectivity based on the kind of operation in a predicate, e.g. $eq, $lt.
*/
SelectivityType heuristicOperationSel(Operations op, CEType inputCard);
/**
* Returns the heuristic selectivity of the given 'interval'.
*/
SelectivityType heuristicIntervalSel(const IntervalRequirement& interval, CEType inputCard);
/**
* Returns the heuristically estimated cardinality of the given 'interval'.
*/
CEType heuristicIntervalCard(const IntervalRequirement& interval, CEType inputCard);
/**
* Returns the heuristic selectivity of an interval expressed as two PathCompare nodes.
*/
SelectivityType heuristicIntervalSel(const PathCompare& left,
const PathCompare& right,
CEType inputCard);
} // namespace mongo::optimizer::ce
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