SERVER-2001 filter queries on mongod using new key extraction path

Queries on mongod must filter out documents that do not currently belong
to the shard.  The belongsToMe function now uses the new key extraction
path to make this determination. An optimization is also added to the
clientcursor class so that it can make this determination using a
covered index if available.

1 files changed, 14 insertions, 0 deletions

diff --git a/src/mongo/db/keypattern.cpp b/src/mongo/db/keypattern.cpp
index 1f3fd6233ec..96229b70fd8 100644
--- a/src/mongo/db/keypattern.cpp
+++ b/src/mongo/db/keypattern.cpp
@@ -47,6 +47,20 @@ namespace mongo {
         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;
+    }
+
     typedef vector<pair<BSONObj,BSONObj> >::const_iterator BoundListIter;
 
     BoundList KeyPattern::keyBounds( const FieldRangeSet& queryConstraints ) const {