Question

I am running updates against a database in MongoLab (Heroku) and cannot get information from getLastError.

As an example, below are statements to update a collection in a MongoDB database running locally in my machine (db version v2.0.3-rc1).

ariels-MacBook:mongodb ariel$ mongo
MongoDB shell version: 2.0.3-rc1
connecting to: test
> db.mycoll.insert({'key': '1','data': 'somevalue'});
> db.mycoll.find();
{ "_id" : ObjectId("505bcc5783cdc9e90ffcddd8"), "key" : "1", "data" : "somevalue" }
> db.mycoll.update({'key': '1'},{$set: {'data': 'anothervalue'}});
> db.runCommand('getlasterror');
{
    "updatedExisting" : true,
    "n" : 1,
    "connectionId" : 4,
    "err" : null,
    "ok" : 1
}
> 

All is well locally.

Now I switch to a database in MongoLab and run the same statements to update a document. getLastError is not returning an updatedExisting field. Hence, I am unable to test if my update was successful or otherwise.

ariels-MacBook:mongodb ariel$ mongo ds0000000.mongolab.com:00000/heroku_app00000 -u someuser -p somepassword
MongoDB shell version: 2.0.3-rc1
connecting to: ds000000.mongolab.com:00000/heroku_app00000
> db.mycoll.insert({'key': '1','data': 'somevalue'});
> db.mycoll.find();
{ "_id" : ObjectId("505bcf9b2421140a6b8490dd"), "key" : "1", "data" : "somevalue" }
> db.mycoll.update({'key': '1'},{$set: {'data': 'anothervalue'}});
> db.runCommand('getlasterror');
{
    "n" : 0,
    "lastOp" : NumberLong("5790450143685771265"),
    "connectionId" : 1097505,
    "err" : null,
    "ok" : 1
}
> db.mycoll.find();
{ "_id" : ObjectId("505bcf9b2421140a6b8490dd"), "data" : "anothervalue", "key" : "1" }
>

Did anyone run into this?
If it matters, my resource at MongoLab is running mongod v2.0.7 (my shell is 2.0.3).
Not exactly sure what I am missing.
I am waiting to hear from their support (I will post here when I hear back) but wanted to check with you fine folks here as well just in case.
Thank you.

Answer 1

This looks to be a limitation of not having admin privileges to the mongod process. You might file a ticket with 10gen as it doesn’t seem like a necessary limitation.

When I run Mongo in auth mode on my laptop I need to authenticate as a user in the admin database in order to see an “n” other than 0 or the “updatedExisting” field. When I authenticate as a user in any other database I get similar results to what you’re seeing in MongoLab production.

(Full disclosure: I work for MongoLab. As a side note, I don’t see the support ticket you mention in our system. We’d be happy to work with you directly if you’d like. You can reach us at [e-mail] or http://support.mongolab.com)