Re: [mongodb-user] Parallel write/delete operations

[Octavian Covalschi]

Have you seen this page? http://www.mongodb.org/display/DOCS/How+does+concurrency+work

On Thu, Oct 4, 2012 at 1:11 PM, OZAYAMA <markus.sc...@googlemail.com> wrote:

Hi List,

I'm new to mongodb and I'm not sure if parallel write/delete operations on one
collection can be a problem.

Use-Case:
---
There's a collection of the name 'message' and my program has two threads.
Thread 'A' adds continuously new documents to the collection 'message' and
thread 'B' removes old documents from the collection 'message' at the same time.
Both threads access the same collection but they operate on different documents.
Does mongodb manage this for me?

Maybe there are other concepts to handle this.

Thanks in advance.

Best Regards

OZ

--
You received this message because you are subscribed to the Google
Groups "mongodb-user" group.
To post to this group, send email to mongod...@googlegroups.com
To unsubscribe from this group, send email to
mongodb-user...@googlegroups.com
See also the IRC channel -- freenode.net#mongodb

[मैं एक भारतीय बेवकूफ हूँ]

http://www.mongodb.org/display/DOCS/How+does+concurrency+work

[OZAYAMA]

Hi,

thanks for the fast response. I've seen that page a couple of days ago so it was a good reminder.
I'll take a look at the following presentation and try to understand what concurrency means in the mongodb world.
https://speakerdeck.com/u/mongodb/p/mongosf-mongodb-concurrency-internals-in-v22

Thanks again.

-OZ

[Octavian Covalschi]

Are you trying to implement some kind of message queue?

[OZAYAMA]

Yes, I'm using rabbitmq for that purpose - thanks for the hint.

-OZ

[OZAYAMA]

FYI,

I've inserted 1.000.000. documents in my 'message' collection and
a concurrent task has deleted the older ones. I've counted all messages
that came in and the number was exactly 1.000.000. So it seems that's
no problem for mongodb to handle concurrent accesses on one collection -
before this test this wasn't clear to me - lack of understanding on my side ;-)

Test Scenario
===

| Client | ===> | MyWebApp | ===> | RabbitMQ | ===> | MyWebApp | ==> | MongoDB |

Prerequisites
===
MongoDB 2.0.4
Grails 2.0.4

-OZ