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// @file keypattern.cpp
/**
* Copyright (C) 2012 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/>.
*
* 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.
*/
#include "mongo/db/keypattern.h"
#include "mongo/db/hasher.h"
#include "mongo/util/mongoutils/str.h"
using namespace mongoutils;
namespace mongo {
KeyPattern::KeyPattern( const BSONObj& pattern ): _pattern( pattern ) {
// Extract all prefixes of each field in pattern.
BSONForEach( field, _pattern ) {
StringData fieldName = field.fieldName();
size_t pos = fieldName.find( '.' );
while ( pos != string::npos ) {
_prefixes.insert( StringData( field.fieldName(), pos ) );
pos = fieldName.find( '.', pos+1 );
}
_prefixes.insert( fieldName );
}
}
bool KeyPattern::isIdKeyPattern(const BSONObj& pattern) {
BSONObjIterator i(pattern);
BSONElement e = i.next();
// _id index must have form exactly {_id : 1} or {_id : -1}.
// Allows an index of form {_id : "hashed"} to exist but
// do not consider it to be the primary _id index
return (0 == strcmp(e.fieldName(), "_id"))
&& (e.numberInt() == 1 || e.numberInt() == -1)
&& i.next().eoo();
}
BSONObj KeyPattern::extractSingleKey(const BSONObj& doc ) const {
if ( _pattern.isEmpty() )
return BSONObj();
if ( mongoutils::str::equals( _pattern.firstElement().valuestrsafe() , "hashed" ) ){
BSONElement fieldVal = doc.getFieldDotted( _pattern.firstElementFieldName() );
return BSON( _pattern.firstElementFieldName() <<
BSONElementHasher::hash64( fieldVal ,
BSONElementHasher::DEFAULT_HASH_SEED ) );
}
return doc.extractFields( _pattern );
}
bool KeyPattern::isSpecial() const {
BSONForEach(e, _pattern) {
int fieldVal = e.numberInt();
if ( fieldVal != 1 && fieldVal != -1 ){
return true;
}
}
return false;
}
bool KeyPattern::isCoveredBy( const KeyPattern& other ) const {
BSONForEach( e, _pattern ) {
BSONElement otherfield = other.getField( e.fieldName() );
if ( otherfield.eoo() ){
return false;
}
if ( otherfield.numberInt() != 1 && otherfield.numberInt() != -1 && otherfield != e ){
return false;
}
}
return true;
}
BSONObj KeyPattern::extendRangeBound( const BSONObj& bound , bool makeUpperInclusive ) const {
BSONObjBuilder newBound( bound.objsize() );
BSONObjIterator src( bound );
BSONObjIterator pat( _pattern );
while( src.more() ){
massert( 16649 ,
str::stream() << "keyPattern " << _pattern << " shorter than bound " << bound,
pat.more() );
BSONElement srcElt = src.next();
BSONElement patElt = pat.next();
massert( 16634 ,
str::stream() << "field names of bound " << bound
<< " do not match those of keyPattern " << _pattern ,
str::equals( srcElt.fieldName() , patElt.fieldName() ) );
newBound.append( srcElt );
}
while( pat.more() ){
BSONElement patElt = pat.next();
// for non 1/-1 field values, like {a : "hashed"}, treat order as ascending
int order = patElt.isNumber() ? patElt.numberInt() : 1;
// flip the order semantics if this is an upper bound
if ( makeUpperInclusive ) order *= -1;
if( order > 0 ){
newBound.appendMinKey( patElt.fieldName() );
}
else {
newBound.appendMaxKey( patElt.fieldName() );
}
}
return newBound.obj();
}
BoundList KeyPattern::keyBounds( const BSONObj& keyPattern, const IndexBounds& indexBounds ) {
invariant(indexBounds.fields.size() == (size_t)keyPattern.nFields());
// If any field is unsatisfied, return empty bound list.
for (vector<OrderedIntervalList>::const_iterator it = indexBounds.fields.begin();
it != indexBounds.fields.end(); it++) {
if (it->intervals.size() == 0) {
return BoundList();
}
}
// To construct our bounds we will generate intervals based on bounds for
// the first field, then compound intervals based on constraints for the first
// 2 fields, then compound intervals for the first 3 fields, etc.
// As we loop through the fields, we start generating new intervals that will later
// get extended in another iteration of the loop. We define these partially constructed
// intervals using pairs of BSONObjBuilders (shared_ptrs, since after one iteration of the
// loop they still must exist outside their scope).
typedef vector< pair< shared_ptr<BSONObjBuilder> ,
shared_ptr<BSONObjBuilder> > > BoundBuilders;
BoundBuilders builders;
builders.push_back( make_pair( shared_ptr<BSONObjBuilder>( new BSONObjBuilder() ),
shared_ptr<BSONObjBuilder>( new BSONObjBuilder() ) ) );
BSONObjIterator keyIter( keyPattern );
// until equalityOnly is false, we are just dealing with equality (no range or $in queries).
bool equalityOnly = true;
for (size_t i = 0; i < indexBounds.fields.size(); i++) {
BSONElement e = keyIter.next();
StringData fieldName = e.fieldNameStringData();
// get the relevant intervals for this field, but we may have to transform the
// list of what's relevant according to the expression for this field
const OrderedIntervalList& oil = indexBounds.fields[i];
const vector<Interval>& intervals = oil.intervals;
if ( equalityOnly ) {
if ( intervals.size() == 1 && intervals.front().isPoint() ){
// this field is only a single point-interval
BoundBuilders::const_iterator j;
for( j = builders.begin(); j != builders.end(); ++j ) {
j->first->appendAs( intervals.front().start, fieldName );
j->second->appendAs( intervals.front().end, fieldName );
}
}
else {
// This clause is the first to generate more than a single point.
// We only execute this clause once. After that, we simplify the bound
// extensions to prevent combinatorial explosion.
equalityOnly = false;
BoundBuilders newBuilders;
for(BoundBuilders::const_iterator it = builders.begin(); it != builders.end(); ++it ) {
BSONObj first = it->first->obj();
BSONObj second = it->second->obj();
for ( vector<Interval>::const_iterator interval = intervals.begin();
interval != intervals.end(); ++interval )
{
uassert( 17439,
"combinatorial limit of $in partitioning of results exceeded" ,
newBuilders.size() < MAX_IN_COMBINATIONS );
newBuilders.push_back(
make_pair( shared_ptr<BSONObjBuilder>( new BSONObjBuilder() ),
shared_ptr<BSONObjBuilder>( new BSONObjBuilder())));
newBuilders.back().first->appendElements( first );
newBuilders.back().second->appendElements( second );
newBuilders.back().first->appendAs( interval->start, fieldName );
newBuilders.back().second->appendAs( interval->end, fieldName );
}
}
builders = newBuilders;
}
}
else {
// if we've already generated a range or multiple point-intervals
// just extend what we've generated with min/max bounds for this field
BoundBuilders::const_iterator j;
for( j = builders.begin(); j != builders.end(); ++j ) {
j->first->appendAs( intervals.front().start, fieldName );
j->second->appendAs( intervals.back().end, fieldName );
}
}
}
BoundList ret;
for( BoundBuilders::const_iterator i = builders.begin(); i != builders.end(); ++i )
ret.push_back( make_pair( i->first->obj(), i->second->obj() ) );
return ret;
}
} // namespace mongo
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