111 lines
3.2 KiB
C++
111 lines
3.2 KiB
C++
/* scanandorder.h
|
|
Order results (that aren't already indexes and in order.)
|
|
*/
|
|
|
|
/**
|
|
* 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 "indexkey.h"
|
|
#include "queryutil.h"
|
|
#include "projection.h"
|
|
|
|
namespace mongo {
|
|
|
|
/* todo:
|
|
_ limit amount of data
|
|
*/
|
|
|
|
class KeyType : boost::noncopyable {
|
|
public:
|
|
IndexSpec _spec;
|
|
FieldRangeVector _keyCutter;
|
|
public:
|
|
KeyType(BSONObj pattern, const FieldRangeSet &frs):
|
|
_spec((assert(!pattern.isEmpty()),pattern)),
|
|
_keyCutter(frs, _spec, 1) {
|
|
}
|
|
|
|
/**
|
|
* @return first key of the object that would be encountered while
|
|
* scanning index with keySpec 'pattern' using constraints 'frs', or
|
|
* BSONObj() if no such key.
|
|
*/
|
|
BSONObj getKeyFromObject(BSONObj o) {
|
|
return _keyCutter.firstMatch(o);
|
|
}
|
|
};
|
|
|
|
/* todo:
|
|
_ respect limit
|
|
_ check for excess mem usage
|
|
_ response size limit from runquery; push it up a bit.
|
|
*/
|
|
|
|
inline void fillQueryResultFromObj(BufBuilder& bb, Projection *filter, const BSONObj& js, DiskLoc* loc=NULL) {
|
|
if ( filter ) {
|
|
BSONObjBuilder b( bb );
|
|
filter->transform( js , b );
|
|
if (loc)
|
|
b.append("$diskLoc", loc->toBSONObj());
|
|
b.done();
|
|
}
|
|
else if (loc) {
|
|
BSONObjBuilder b( bb );
|
|
b.appendElements(js);
|
|
b.append("$diskLoc", loc->toBSONObj());
|
|
b.done();
|
|
}
|
|
else {
|
|
bb.appendBuf((void*) js.objdata(), js.objsize());
|
|
}
|
|
}
|
|
|
|
typedef multimap<BSONObj,BSONObj,BSONObjCmp> BestMap;
|
|
class ScanAndOrder {
|
|
public:
|
|
static const unsigned MaxScanAndOrderBytes;
|
|
|
|
ScanAndOrder(int startFrom, int limit, BSONObj order, const FieldRangeSet &frs) :
|
|
_best( BSONObjCmp( order ) ),
|
|
_startFrom(startFrom), _order(order, frs) {
|
|
_limit = limit > 0 ? limit + _startFrom : 0x7fffffff;
|
|
_approxSize = 0;
|
|
}
|
|
|
|
int size() const { return _best.size(); }
|
|
|
|
void add(BSONObj o, DiskLoc* loc);
|
|
|
|
/* scanning complete. stick the query result in b for n objects. */
|
|
void fill(BufBuilder& b, Projection *filter, int& nout ) const;
|
|
|
|
private:
|
|
|
|
void _add(BSONObj& k, BSONObj o, DiskLoc* loc);
|
|
|
|
void _addIfBetter(BSONObj& k, BSONObj o, BestMap::iterator i, DiskLoc* loc);
|
|
|
|
BestMap _best; // key -> full object
|
|
int _startFrom;
|
|
int _limit; // max to send back.
|
|
KeyType _order;
|
|
unsigned _approxSize;
|
|
|
|
};
|
|
|
|
} // namespace mongo
|