From 32d5099884dff243ee0589d23300f957712abd4a Mon Sep 17 00:00:00 2001
From: Adam Monsen <haircut@gmail.com>
Date: Thu, 7 May 2015 08:36:38 -0700
Subject: [PATCH] don't add {safe:true} to MongoDB indexes
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Based on the log message in e38cefbc0466167e4bf5a19010f8ba1a1e4aca62 the
original intent of passing `{safe:true}` in the `_ensureIndex()` options
was to emulate MongoDB's `createIndex()` (neé `ensureIndex()`) setting
`{unique:true}`. Unfortunately, `{safe:true}` does not throw an error if
duplicate data is found. That's what `{unique:true}` is for.
`{safe:true}` simply adds the key `safe` with the value `true` to the
index document.

Here's an illustration. Create a new collection:

  mongo> db.people.drop()
  mongo> db.people.insert({name:'Samus'})
  mongo> db.people.insert({name:'Samus'})
  mongo> db.people.find()
  {"_id": ObjectId("554b85018152d2b363cbc1d8"), "name": "Adam" }
  {"_id": ObjectId("554b85088152d2b363cbc1d9"), "name": "Adam" }

In a Meteor app, add:

  if (Meteor.isServer) {
    Meteor.startup(function() {
      People = new Mongo.Collection('people');
      People._ensureIndex({name:1});
    }
  }

Configure the app to connect to the above MongoDB server/database and
start the app. No error is thrown, and a nonunique index is created with
a `safe` key that (as far as I can tell) has no effect:

  mongo> db.people.getIndexes()[1]
  {
    "v": 1,
    "key": {
      "name": 1
    },
    "name": "name_1",
    "ns": "test.people",
    "safe": true
  }

MongoDB appears to store arbitrary keys on indexes. Anything in
`options` is just shoved right in. Demonstration:

  mongo> db.people.dropIndex('name_1')
  mongo> db.people.createIndex({name:1},{Castlevania:false,Metroid:true})
  mongo> db.people.getIndexes()[1]
  {
    "v": 1,
    "key": {
      "name": 1
    },
    "name": "name_1",
    "ns": "test.people",
    "Castlevania": false,
    "Metroid": true
  }
---
 packages/mongo/mongo_driver.js | 1 -
 1 file changed, 1 deletion(-)

diff --git a/packages/mongo/mongo_driver.js b/packages/mongo/mongo_driver.js
index 43410fff8e..a9327b20d9 100644
--- a/packages/mongo/mongo_driver.js
+++ b/packages/mongo/mongo_driver.js
@@ -742,7 +742,6 @@ MongoConnection.prototype.findOne = function (collection_name, selector,
 MongoConnection.prototype._ensureIndex = function (collectionName, index,
                                                    options) {
   var self = this;
-  options = _.extend({safe: true}, options);
 
   // We expect this function to be called at startup, not from within a method,
   // so we don't interact with the write fence.