mirror of https://gitee.com/bigwinds/arangodb
124 lines
4.0 KiB
C++
124 lines
4.0 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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/// DISCLAIMER
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///
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/// Copyright 2018 ArangoDB GmbH, Cologne, Germany
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///
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/// Licensed under the Apache License, Version 2.0 (the "License");
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/// you may not use this file except in compliance with the License.
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/// You may obtain a copy of the License at
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///
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/// http://www.apache.org/licenses/LICENSE-2.0
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///
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/// Unless required by applicable law or agreed to in writing, software
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/// distributed under the License is distributed on an "AS IS" BASIS,
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/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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/// See the License for the specific language governing permissions and
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/// limitations under the License.
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///
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/// Copyright holder is ArangoDB GmbH, Cologne, Germany
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///
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/// @author Tobias Goedderz
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/// @author Michael Hackstein
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/// @author Heiko Kernbach
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/// @author Jan Christoph Uhde
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////////////////////////////////////////////////////////////////////////////////
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#ifndef ARANGOD_AQL_DISTINCT_COLLECT_EXECUTOR_H
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#define ARANGOD_AQL_DISTINCT_COLLECT_EXECUTOR_H
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#include "Aql/AqlValueGroup.h"
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#include "Aql/ExecutionBlock.h"
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#include "Aql/ExecutionBlockImpl.h"
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#include "Aql/ExecutionNode.h"
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#include "Aql/ExecutionState.h"
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#include "Aql/ExecutorInfos.h"
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#include "Aql/LimitStats.h"
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#include "Aql/OutputAqlItemRow.h"
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#include "Aql/types.h"
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#include <memory>
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namespace arangodb {
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namespace aql {
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class InputAqlItemRow;
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class ExecutorInfos;
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template <bool>
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class SingleRowFetcher;
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class DistinctCollectExecutorInfos : public ExecutorInfos {
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public:
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DistinctCollectExecutorInfos(RegisterId nrInputRegisters, RegisterId nrOutputRegisters,
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std::unordered_set<RegisterId> registersToClear,
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std::unordered_set<RegisterId> registersToKeep,
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std::unordered_set<RegisterId>&& readableInputRegisters,
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std::unordered_set<RegisterId>&& writeableInputRegisters,
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std::vector<std::pair<RegisterId, RegisterId>>&& groupRegisters,
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transaction::Methods* trxPtr);
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DistinctCollectExecutorInfos() = delete;
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DistinctCollectExecutorInfos(DistinctCollectExecutorInfos&&) = default;
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DistinctCollectExecutorInfos(DistinctCollectExecutorInfos const&) = delete;
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~DistinctCollectExecutorInfos() = default;
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public:
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std::vector<std::pair<RegisterId, RegisterId>> getGroupRegisters() const {
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return _groupRegisters;
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}
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transaction::Methods* getTransaction() const { return _trxPtr; }
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private:
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/// @brief pairs, consisting of out register and in register
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std::vector<std::pair<RegisterId, RegisterId>> _groupRegisters;
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/// @brief the transaction for this query
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transaction::Methods* _trxPtr;
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};
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/**
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* @brief Implementation of Distinct Collect Executor
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*/
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class DistinctCollectExecutor {
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public:
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struct Properties {
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static const bool preservesOrder = false;
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static const bool allowsBlockPassthrough = false;
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static const bool inputSizeRestrictsOutputSize = true;
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};
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using Fetcher = SingleRowFetcher<Properties::allowsBlockPassthrough>;
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using Infos = DistinctCollectExecutorInfos;
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using Stats = NoStats;
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DistinctCollectExecutor() = delete;
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DistinctCollectExecutor(DistinctCollectExecutor&&) = default;
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DistinctCollectExecutor(DistinctCollectExecutor const&) = delete;
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DistinctCollectExecutor(Fetcher& fetcher, Infos&);
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~DistinctCollectExecutor();
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void initializeCursor();
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/**
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* @brief produce the next Row of Aql Values.
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*
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* @return ExecutionState, and if successful exactly one new Row of AqlItems.
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*/
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std::pair<ExecutionState, Stats> produceRows(OutputAqlItemRow& output);
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std::pair<ExecutionState, size_t> expectedNumberOfRows(size_t atMost) const;
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private:
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Infos const& infos() const noexcept { return _infos; };
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void destroyValues();
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private:
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Infos const& _infos;
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Fetcher& _fetcher;
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std::unordered_set<std::vector<AqlValue>, AqlValueGroupHash, AqlValueGroupEqual> _seen;
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};
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} // namespace aql
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} // namespace arangodb
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#endif
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