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This commit is contained in:
Eliot Horowitz 2010-09-13 01:21:20 -04:00
parent 47f19103ac
commit dd1a25d458
2 changed files with 58 additions and 34 deletions
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85
s/chunk.cpp
View File

@ -82,45 +82,56 @@ namespace mongo {
bool Chunk::maxIsInf() const {
return _manager->getShardKey().globalMax().woCompare( getMax() ) == 0;
}
BSONObj Chunk::pickSplitPoint( const vector<BSONObj> * possibleSplitPoints ) const{
int sort = 0;
if ( minIsInf() ){
sort = 1;
BSONObj Chunk::_getExtremeKey( int sort ) const {
ShardConnection conn( getShard().getConnString() , _manager->getns() );
Query q;
if ( sort == 1 ) {
q.sort( _manager->getShardKey().key() );
}
else if ( maxIsInf() ){
sort = -1;
}
if ( sort ){
ShardConnection conn( getShard().getConnString() , _manager->getns() );
Query q;
if ( sort == 1 )
q.sort( _manager->getShardKey().key() );
else {
BSONObj k = _manager->getShardKey().key();
BSONObjBuilder r;
BSONObjIterator i(k);
while( i.more() ) {
BSONElement e = i.next();
uassert( 10163 , "can only handle numbers here - which i think is correct" , e.isNumber() );
r.append( e.fieldName() , -1 * e.number() );
}
q.sort( r.obj() );
else {
// need to invert shard key pattern to sort backwards
// TODO: make a helper in ShardKeyPattern?
BSONObj k = _manager->getShardKey().key();
BSONObjBuilder r;
BSONObjIterator i(k);
while( i.more() ) {
BSONElement e = i.next();
uassert( 10163 , "can only handle numbers here - which i think is correct" , e.isNumber() );
r.append( e.fieldName() , -1 * e.number() );
}
BSONObj end = conn->findOne( _manager->getns() , q );
conn.done();
if ( ! end.isEmpty() )
return _manager->getShardKey().extractKey( end );
q.sort( r.obj() );
}
// find the extreme key
BSONObj end = conn->findOne( _manager->getns() , q );
conn.done();
if ( end.isEmpty() )
return BSONObj();
return _manager->getShardKey().extractKey( end );
}
BSONObj Chunk::pickSplitPoint( const vector<BSONObj> * possibleSplitPoints ) const {
// check to see if we're at the edge of the key range
// if so, split on the edge for sequential insertion efficienc
if ( minIsInf() )
return _getExtremeKey( 1 );
if ( maxIsInf() )
return _getExtremeKey( -1 );
// we're not at an edge, so use the hint if we have one
if ( possibleSplitPoints && possibleSplitPoints->size() )
return possibleSplitPoints->at(0);
// no edge, no hint, so find the median of the range
BSONObj cmd = BSON( "medianKey" << _manager->getns()
<< "keyPattern" << _manager->getShardKey().key()
<< "min" << getMin()
@ -136,7 +147,12 @@ namespace mongo {
BSONObj median = result.getObjectField( "median" ).getOwned();
if (median == getMin()){
if ( median == getMin() ) {
// if the median is the same as the min
// we don't want to split on the median,
// but the maximum real value
// otherwise we'll never be able to split up a chunk with lots of key dups
Query q;
q.minKey(_min).maxKey(_max);
q.sort(_manager->getShardKey().key());
@ -146,7 +162,8 @@ namespace mongo {
}
conn.done();
// sanity check median - purely defensive
if ( median < getMin() || median >= getMax() ){
stringstream ss;
ss << "medianKey returned value out of range. "

7
s/chunk.h
View File

@ -147,6 +147,13 @@ namespace mongo {
bool _splitIfShould( long dataWritten );
ChunkPtr multiSplit_inlock( const vector<BSONObj>& splitPoints );
/**
* if sort 1, return lowest key
* if sort -1, return highest key
* will return empty object if have none
*/
BSONObj _getExtremeKey( int sort ) const;
// main shard info
ChunkManager * _manager;