Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

94 lines (80 sloc) 3.161 kb
/* scanandorder.cpp
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/>.
*/
#include "pch.h"
#include "scanandorder.h"
namespace mongo {
const unsigned ScanAndOrder::MaxScanAndOrderBytes = 32 * 1024 * 1024;
void ScanAndOrder::_add(BSONObj& k, BSONObj o, DiskLoc* loc) {
if (!loc) {
_best.insert(make_pair(k.getOwned(),o.getOwned()));
}
else {
BSONObjBuilder b;
b.appendElements(o);
b.append("$diskLoc", loc->toBSONObj());
_best.insert(make_pair(k.getOwned(), b.obj().getOwned()));
}
}
void ScanAndOrder::_addIfBetter(BSONObj& k, BSONObj o, BestMap::iterator i, DiskLoc* loc) {
/* todo : we don't correct _approxSize here. */
const BSONObj& worstBestKey = i->first;
int c = worstBestKey.woCompare(k, _order._spec.keyPattern);
if ( c > 0 ) {
// k is better, 'upgrade'
_best.erase(i);
_add(k, o, loc);
}
}
void ScanAndOrder::add(BSONObj o, DiskLoc* loc) {
assert( o.isValid() );
BSONObj k = _order.getKeyFromObject(o);
if ( k.isEmpty() ) {
return;
}
if ( (int) _best.size() < _limit ) {
_approxSize += k.objsize();
_approxSize += o.objsize();
/* note : adjust when bson return limit adjusts. note this limit should be a bit higher. */
uassert( 10128 , "too much data for sort() with no index. add an index or specify a smaller limit", _approxSize < MaxScanAndOrderBytes );
_add(k, o, loc);
return;
}
BestMap::iterator i;
assert( _best.end() != _best.begin() );
i = _best.end();
i--;
_addIfBetter(k, o, i, loc);
}
void ScanAndOrder::fill(BufBuilder& b, Projection *filter, int& nout ) const {
int n = 0;
int nFilled = 0;
for ( BestMap::const_iterator i = _best.begin(); i != _best.end(); i++ ) {
n++;
if ( n <= _startFrom )
continue;
const BSONObj& o = i->second;
fillQueryResultFromObj(b, filter, o);
nFilled++;
if ( nFilled >= _limit )
break;
uassert( 10129 , "too much data for sort() with no index", b.len() < (int)MaxScanAndOrderBytes ); // appserver limit
}
nout = nFilled;
}
} // namespace mongo
Jump to Line
Something went wrong with that request. Please try again.