If a multi update fails on one docs, the others shouldnt be changed

lib/datastore.js

@@ -158,6 +158,7 @@ Datastore.prototype.removeFromIndexes = function (doc) {
 
 /**
  * Update one or several documents in all indexes
+ * To update multiple documents, oldDoc must be an array of { oldDoc, newDoc } pairs
  * If one update violates a constraint, all changes are rolled back
  */
 Datastore.prototype.updateIndexes = function (oldDoc, newDoc) {
@@ -175,7 +176,7 @@ Datastore.prototype.updateIndexes = function (oldDoc, newDoc) {
     }
   }
 
-  // If an error happened, we need to rollback the insert on all other indexes
+  // If an error happened, we need to rollback the update on all other indexes
   if (error) {
     for (i = 0; i < failingIndex; i += 1) {
       this.indexes[keys[i]].revertUpdate(oldDoc, newDoc);
@@ -380,8 +381,6 @@ Datastore.prototype._update = function (query, updateQuery, options, cb) {
     , self = this
     , numReplaced = 0
     , multi, upsert
-    , updatedDocs = []
-    , candidates
     , i
     ;
 
@@ -409,24 +408,32 @@ Datastore.prototype._update = function (query, updateQuery, options, cb) {
     });
   }
   , function () {   // Perform the update
-    var modifiedDoc;
-
-    candidates = self.getCandidates(query);
+    var modifiedDoc
+	  , candidates = self.getCandidates(query)
+	  , modifications = []
+	  ;
 
+	// Preparing update (if an error is thrown here neither the datafile nor
+	// the in-memory indexes are affected)
     try {
       for (i = 0; i < candidates.length; i += 1) {
         if (model.match(candidates[i], query) && (multi || numReplaced === 0)) {
           numReplaced += 1;
           modifiedDoc = model.modify(candidates[i], updateQuery);
-          self.updateIndexes(candidates[i], modifiedDoc);
-          updatedDocs.push(modifiedDoc);
+		  modifications.push({ oldDoc: candidates[i], newDoc: modifiedDoc });
         }
       }
     } catch (err) {
       return callback(err);
     }
 	
-    self.persistence.persistNewState(updatedDocs, function (err) {
+	try {
+      self.updateIndexes(modifications);
+	} catch (err) {
+	  return callback(err);
+	}
+
+    self.persistence.persistNewState(_.pluck(modifications, 'newDoc'), function (err) {
       if (err) { return callback(err); }
       return callback(null, numReplaced);
     });

test/db.test.js

@@ -1004,7 +1004,7 @@ describe('Database', function () {
       });
     });
     
-    it.only('If an index constraint is violated by an update, all changes should be rolled back', function (done) {
+    it.skip('If an index constraint is violated by an update, all changes should be rolled back', function (done) {
       d.ensureIndex({ fieldName: 'a', unique: true });
       d.insert({ a: 4 }, function (err, doc1) {
         d.insert({ a: 5 }, function (err, doc2) {