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/* queryoptimizer.h */
/**
* Copyright (C) 2008 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"
#include "jsobj.h"
#include "queryutil.h"
namespace mongo {
class IndexDetails;
class QueryPlan {
public:
QueryPlan( const FieldBoundSet &fbs, const BSONObj &order, const IndexDetails *index = 0 );
QueryPlan( const QueryPlan &other );
/* If true, no other index can do better. */
bool optimal() const { return optimal_; }
/* ScanAndOrder processing will be required if true */
bool scanAndOrderRequired() const { return scanAndOrderRequired_; }
/* When true, the index we are using has keys such that it can completely resolve the
query expression to match by itself without ever checking the main object.
*/
bool keyMatch() const { return keyMatch_; }
/* True if keyMatch() is true, and all matches will be equal according to woEqual() */
bool exactKeyMatch() const { return exactKeyMatch_; }
/* If true, the startKey and endKey are unhelpful, the index order doesn't match the
requested sort order, and keyMatch is false */
bool unhelpful() const { return unhelpful_; }
int direction() const { return direction_; }
BSONObj startKey() const { return startKey_; }
BSONObj endKey() const { return endKey_; }
auto_ptr< Cursor > newCursor( const DiskLoc &startLoc = DiskLoc() ) const;
auto_ptr< Cursor > newReverseCursor() const;
BSONObj indexKey() const;
const char *ns() const { return fbs_.ns(); }
BSONObj query() const { return fbs_.query(); }
const FieldBound &bound( const char *fieldName ) const { return fbs_.bound( fieldName ); }
void registerSelf( long long nScanned ) const;
private:
const FieldBoundSet &fbs_;
const BSONObj &order_;
const IndexDetails *index_;
bool optimal_;
bool scanAndOrderRequired_;
bool keyMatch_;
bool exactKeyMatch_;
int direction_;
BSONObj startKey_;
BSONObj endKey_;
bool unhelpful_;
};
// Inherit from this interface to implement a new query operation.
class QueryOp {
public:
QueryOp() : complete_(), qp_(), error_() {}
virtual ~QueryOp() {}
virtual void init() = 0;
virtual void next() = 0;
virtual bool mayRecordPlan() const = 0;
// Return a copy of the inheriting class, which will be run with its own
// query plan.
virtual QueryOp *clone() const = 0;
bool complete() const { return complete_; }
bool error() const { return error_; }
string exceptionMessage() const { return exceptionMessage_; }
const QueryPlan &qp() const { return *qp_; }
// To be called by QueryPlanSet::Runner only.
void setQueryPlan( const QueryPlan *qp ) { qp_ = qp; }
void setExceptionMessage( const string &exceptionMessage ) {
error_ = true;
exceptionMessage_ = exceptionMessage;
}
protected:
void setComplete() { complete_ = true; }
private:
bool complete_;
string exceptionMessage_;
const QueryPlan *qp_;
bool error_;
};
class QueryPlanSet {
public:
QueryPlanSet( const char *ns, const BSONObj &query, const BSONObj &order, const BSONElement *hint = 0, bool honorRecordedPlan = true );
int nPlans() const { return plans_.size(); }
shared_ptr< QueryOp > runOp( QueryOp &op );
template< class T >
shared_ptr< T > runOp( T &op ) {
return dynamic_pointer_cast< T >( runOp( static_cast< QueryOp& >( op ) ) );
}
const FieldBoundSet &fbs() const { return fbs_; }
BSONObj explain() const;
bool usingPrerecordedPlan() const { return usingPrerecordedPlan_; }
private:
void addOtherPlans( bool checkFirst );
typedef boost::shared_ptr< QueryPlan > PlanPtr;
typedef vector< PlanPtr > PlanSet;
void addPlan( PlanPtr plan, bool checkFirst ) {
if ( checkFirst && plan->indexKey().woCompare( plans_[ 0 ]->indexKey() ) == 0 )
return;
plans_.push_back( plan );
}
void init();
struct Runner {
Runner( QueryPlanSet &plans, QueryOp &op );
shared_ptr< QueryOp > run();
QueryOp &op_;
QueryPlanSet &plans_;
static void initOp( QueryOp &op );
static void nextOp( QueryOp &op );
};
FieldBoundSet fbs_;
PlanSet plans_;
bool mayRecordPlan_;
bool usingPrerecordedPlan_;
BSONObj hint_;
BSONObj order_;
long long oldNScanned_;
bool honorRecordedPlan_;
};
} // namespace mongo
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