--- mongo-git/db/update.h	2011-02-06 13:30:47.000000000 -0200
+++ mongo/db/update.h	2011-02-06 13:38:13.000000000 -0200
@@ -32,8 +32,8 @@
      */
     struct Mod {
         // See opFromStr below
-        //        0    1    2     3         4     5          6    7      8       9       10    11        12           13
-        enum Op { INC, SET, PUSH, PUSH_ALL, PULL, PULL_ALL , POP, UNSET, BITAND, BITOR , BIT , ADDTOSET, RENAME_FROM, RENAME_TO } op;
+        //        0    1    2     3         4     5          6    7      8       9       10    11        12           13         14
+        enum Op { INC, SET, PUSH, PUSH_ALL, PULL, PULL_ALL , POP, UNSET, BITAND, BITOR , BIT , ADDTOSET, RENAME_FROM, RENAME_TO, MULTIPLY } op;
 
         static const char* modNames[];
         static unsigned modNamesNum;
@@ -108,6 +108,8 @@
 
         template< class Builder >
         void appendIncremented( Builder& bb , const BSONElement& in, ModState& ms ) const;
+        template< class Builder >
+        void appendMultiplied( Builder& bb , const BSONElement& in, ModState& ms ) const;
 
         bool operator<( const Mod &other ) const {
             return strcmp( fieldName, other.fieldName ) < 0;
@@ -339,6 +341,10 @@
                 }
                 break;
             }
+            case 'm': {
+                if ( fn[2] == 'u' && fn[3] == 'l' && fn[4] == 't' && fn[5] == 'i' && fn[6] == 'p' && fn[7] == 'l' && fn[8] == 'y')
+                        return Mod::MULTIPLY;
+            }
             default: break;
             }
             uassert( 10161 ,  "Invalid modifier specified " + string( fn ), false );
--- mongo-git/db/update.cpp	2011-02-06 13:30:47.000000000 -0200
+++ mongo/db/update.cpp	2011-02-06 13:34:08.000000000 -0200
@@ -84,6 +84,27 @@
     }
 
     template< class Builder >
+    void Mod::appendMultiplied( Builder& bb , const BSONElement& in, ModState& ms ) const {
+        BSONType a = in.type();
+        BSONType b = elt.type();
+        
+        if ( a == NumberDouble || b == NumberDouble ){
+            ms.incType = NumberDouble;
+            ms.incdouble = elt.numberDouble() * in.numberDouble();
+        }
+        else if ( a == NumberLong || b == NumberLong ){
+            ms.incType = NumberLong;
+            ms.inclong = elt.numberLong() * in.numberLong();
+        }
+        else {
+            ms.incType = NumberInt;
+            ms.incint = elt.numberInt() * in.numberInt();
+        }
+        
+        ms.appendIncValue( bb , false );
+    }
+
+    template< class Builder >
     void appendUnset( Builder &b ) {
     }
 
@@ -331,6 +352,11 @@
             break;
         }
 
+        case MULTIPLY: {
+            appendMultiplied( b , in , ms );
+            break;
+        }
+            
         default:
             stringstream ss;
             ss << "Mod::apply can't handle type: " << op;