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/**
* Copyright (C) 2014 MongoDB 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 "mongo/db/exec/plan_stage.h"
#include "mongo/db/index/index_access_method.h"
#include "mongo/db/index/index_descriptor.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/matcher/expression.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/record_id.h"
#include "mongo/stdx/unordered_set.h"
namespace mongo {
class WorkingSet;
struct CountScanParams {
CountScanParams(const IndexDescriptor& descriptor,
std::string indexName,
BSONObj keyPattern,
MultikeyPaths multikeyPaths,
bool multikey)
: accessMethod(descriptor.getIndexCatalog()->getIndex(&descriptor)),
name(std::move(indexName)),
keyPattern(std::move(keyPattern)),
multikeyPaths(std::move(multikeyPaths)),
isMultiKey(multikey),
isSparse(descriptor.isSparse()),
isUnique(descriptor.unique()),
isPartial(descriptor.isPartial()),
version(descriptor.version()),
collation(descriptor.infoObj()
.getObjectField(IndexDescriptor::kCollationFieldName)
.getOwned()) {
invariant(accessMethod);
}
CountScanParams(OperationContext* opCtx, const IndexDescriptor& descriptor)
: CountScanParams(descriptor,
descriptor.indexName(),
descriptor.keyPattern(),
descriptor.getMultikeyPaths(opCtx),
descriptor.isMultikey(opCtx)) {}
const IndexAccessMethod* accessMethod;
std::string name;
BSONObj keyPattern;
MultikeyPaths multikeyPaths;
bool isMultiKey;
bool isSparse;
bool isUnique;
bool isPartial;
IndexDescriptor::IndexVersion version;
BSONObj collation;
BSONObj startKey;
bool startKeyInclusive{true};
BSONObj endKey;
bool endKeyInclusive{true};
};
/**
* Used by the count command. Scans an index from a start key to an end key. Creates a
* WorkingSetMember for each matching index key in RID_AND_OBJ state. It has a null record id and an
* empty object with a null snapshot id rather than real data. Returning real data is unnecessary
* since all we need is the count.
*
* Only created through the getExecutorCount() path, as count is the only operation that doesn't
* care about its data.
*/
class CountScan final : public PlanStage {
public:
CountScan(OperationContext* opCtx, CountScanParams params, WorkingSet* workingSet);
StageState doWork(WorkingSetID* out) final;
bool isEOF() final;
void doSaveState() final;
void doRestoreState() final;
void doDetachFromOperationContext() final;
void doReattachToOperationContext() final;
StageType stageType() const final {
return STAGE_COUNT_SCAN;
}
std::unique_ptr<PlanStageStats> getStats() final;
const SpecificStats* getSpecificStats() const final;
static const char* kStageType;
private:
// The WorkingSet we annotate with results. Not owned by us.
WorkingSet* _workingSet;
// Index access. The pointer below is owned by Collection -> IndexCatalog.
const IndexAccessMethod* _iam;
std::unique_ptr<SortedDataInterface::Cursor> _cursor;
// Could our index have duplicates? If so, we use _returned to dedup.
const bool _shouldDedup;
stdx::unordered_set<RecordId, RecordId::Hasher> _returned;
CountScanParams _params;
CountScanStats _specificStats;
};
} // namespace mongo
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