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/**
* Copyright (C) 2018-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/index/index_access_method.h"
#include "mongo/db/index/wildcard_key_generator.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/query/index_bounds.h"
namespace mongo {
/**
* Class which is responsible for generating and providing access to Wildcard index keys. Any index
* created with { "$**": ±1 } or { "path.$**": ±1 } uses this class.
*
* $** indexes store a special metadata key for each path in the index that is multikey. This class
* provides an interface to access the multikey metadata: see getMultikeyPaths().
*/
class WildcardAccessMethod final : public AbstractIndexAccessMethod {
public:
/**
* Returns an exact set or super-set of the bounds required to fetch the multikey metadata keys
* relevant to 'field'.
*/
static std::vector<Interval> getMultikeyPathIndexIntervalsForField(FieldRef field);
/**
* Extracts the multikey path from a metadata key stored within a wildcard index.
*/
static FieldRef extractMultikeyPathFromIndexKey(const IndexKeyEntry& entry);
WildcardAccessMethod(IndexCatalogEntry* wildcardState, SortedDataInterface* btree);
/**
* Returns 'true' if the index should become multikey on the basis of the passed arguments.
* Because it is possible for a $** index to generate multiple keys per document without any of
* them lying along a multikey (i.e. array) path, this method will only return 'true' if one or
* more multikey metadata keys have been generated; that is, if the 'multikeyMetadataKeys'
* BSONObjSet is non-empty.
*/
bool shouldMarkIndexAsMultikey(const BSONObjSet& keys,
const BSONObjSet& multikeyMetadataKeys,
const MultikeyPaths& multikeyPaths) const final;
/**
* Returns a pointer to the ProjectionExecAgg owned by the underlying WildcardKeyGenerator.
*/
const ProjectionExecAgg* getProjectionExec() const {
return _keyGen.getProjectionExec();
}
/**
* Returns the intersection of 'fieldSet' and the set of paths for which the $** has multikey
* metadata keys.
*/
std::set<FieldRef> getMultikeyPathSet(OperationContext*,
const stdx::unordered_set<std::string>& fieldSet,
MultikeyMetadataAccessStats* stats) const final;
/**
* Returns the entire set of paths for which the $** has multikey metadata keys.
*/
std::set<FieldRef> getMultikeyPathSet(OperationContext* opCtx,
MultikeyMetadataAccessStats* stats) const final;
private:
void doGetKeys(const BSONObj& obj,
BSONObjSet* keys,
BSONObjSet* multikeyMetadataKeys,
MultikeyPaths* multikeyPaths) const final;
std::set<FieldRef> _getMultikeyPathSet(OperationContext* opCtx,
const IndexBounds& indexBounds,
MultikeyMetadataAccessStats* stats) const;
const WildcardKeyGenerator _keyGen;
};
} // namespace mongo
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