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/**
* Copyright (C) 2011 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/>.
*/
#pragma once
#include "cursor.h"
namespace mongo {
class CandidatePlanCharacter;
class ExplainQueryInfo;
class FieldRangeSet;
/**
* Adds functionality to Cursor for running multiple plans, running out of order plans,
* utilizing covered indexes, and generating explain output.
*/
class QueryOptimizerCursor : public Cursor {
public:
/** Candidate plans for the query before it begins running. */
virtual CandidatePlanCharacter initialCandidatePlans() const = 0;
/** FieldRangeSet for the query before it begins running. */
virtual const FieldRangeSet *initialFieldRangeSet() const = 0;
/** @return true if the plan for the current iterate is out of order. */
virtual bool currentPlanScanAndOrderRequired() const = 0;
/** @return true when there may be multiple plans running and some are in order. */
virtual bool runningInitialInOrderPlan() const = 0;
/**
* @return true when some query plans may have been excluded due to plan caching, for a
* non-$or query.
*/
virtual bool hasPossiblyExcludedPlans() const = 0;
/**
* @return true when both in order and out of order candidate plans were available, and
* an out of order candidate plan completed iteration.
*/
virtual bool completePlanOfHybridSetScanAndOrderRequired() const = 0;
/** Clear recorded indexes for the current clause's query patterns. */
virtual void clearIndexesForPatterns() = 0;
/** Stop returning results from out of order plans and do not allow them to complete. */
virtual void abortOutOfOrderPlans() = 0;
/** Note match information for the current iterate, to generate explain output. */
virtual void noteIterate( bool match, bool loadedDocument, bool chunkSkip ) = 0;
/** Note a lock yield for explain output reporting. */
virtual void noteYield() = 0;
/** @return explain output for the query run by this cursor. */
virtual shared_ptr<ExplainQueryInfo> explainQueryInfo() const = 0;
};
} // namespace mongo
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