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Diffstat (limited to 'src/mongo/db/query/plan_cache_indexability.h')
-rw-r--r-- | src/mongo/db/query/plan_cache_indexability.h | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/src/mongo/db/query/plan_cache_indexability.h b/src/mongo/db/query/plan_cache_indexability.h new file mode 100644 index 00000000000..aef3a863e98 --- /dev/null +++ b/src/mongo/db/query/plan_cache_indexability.h @@ -0,0 +1,87 @@ +/** + * Copyright (C) 2015 10gen Inc. + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU Affero General Public License, version 3, + * as published by the Free Software Foundation. + * + * 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 + * GNU Affero General Public License for more details. + * + * You should have received a copy of the GNU Affero General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + * + * 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 GNU Affero General 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 <vector> + +#include "mongo/base/disallow_copying.h" +#include "mongo/stdx/functional.h" +#include "mongo/util/string_map.h" + +namespace mongo { + + class BSONObj; + class MatchExpression; + struct IndexEntry; + + using IndexabilityDiscriminator = stdx::function<bool(const MatchExpression* me)>; + using IndexabilityDiscriminators = std::vector<IndexabilityDiscriminator>; + + /** + * PlanCacheIndexabilityState holds a set of "indexability discriminators" for certain paths. + * An indexability discriminator is a binary predicate function, used to classify match + * expressions based on the data values in the expression. + */ + class PlanCacheIndexabilityState { + MONGO_DISALLOW_COPYING(PlanCacheIndexabilityState); + public: + PlanCacheIndexabilityState() = default; + + /** + * Gets the set of discriminators associated with 'path'. Returns an empty set if no + * discriminators are registered for 'path'. + * + * The object returned by reference is valid until the next call to updateDiscriminators() + * or until destruction of 'this', whichever is first. + */ + const IndexabilityDiscriminators& getDiscriminators(StringData path) const; + + /** + * Clears discriminators for all paths, and regenerate them from 'indexEntries'. + */ + void updateDiscriminators(const std::vector<IndexEntry>& indexEntries); + + private: + /** + * Adds partial index discriminators for the partial index with the given filter expression + * to '_pathDiscriminatorsMap'. + * + * A partial index discriminator distinguishes expressions that match a given partial index + * predicate from expressions that don't match the partial index predicate. For example, + * this allows the predicate {a: {$gt: 5}} to be considered a different shape than the + * predicate {a: {$gt: -5}}, if there is a partial index defined with document filter {a: + * {$gt: 0}}. The former is compatible with this index, but the latter is not compatible. + */ + void processPartialIndex(const MatchExpression* filterExpr); + + using PathDiscriminatorsMap = StringMap<IndexabilityDiscriminators>; + PathDiscriminatorsMap _pathDiscriminatorsMap; + }; + +} // namespace mongo |