MongoDB 2.6 Released

[danielrpa]

A lot of hype... And we still have db level locking. If document level is too difficult, at LEAST do collection level (not that it is too much better, but least it some real improvement).

[z92]

I was reading somewhere that Mongo can't do document level/record level locking because of mmap'ed files. The whole database is memory mapped. And mmap doesn't understand underlined data structure, it views the whole file as a large single blob.

Ditching mmap will not be that easy, cause most of the speed and simplicity of Mongo comes from using mmap.

[sigzero]

"Finally, MongoDB 2.6 lays the foundation for massive improvements to concurrency in MongoDB 2.8, including document-level locking."

They hear you and are working on it.

[rogerbinns]

Heck I'd even be happy for them to do locking on a per file basis. (For those unfamiliar with mongodb, the actual database storage is broken up into 2GB files.)

[disbelief]

Every Mongo release announcement I hold out hope for an improvement to database-level write lock, and every time I'm disappointing. Considering this is probably the #1 or #2 complaint people have with Mongo, I'm surprised it hasn't been addressed ahead of some of the other features that have made it in to recent releases.

[Kiro]

I don't know anything about MongoDB but can you give an example where DB level locking is a problem?

[fiatmoney]

And it still relies entirely on the OS's scheduling algorithms for caching and IO. mmap is nice but it has no idea you're running a database.

[lazyloop]

Here are the release notes. http://docs.mongodb.org/master/release-notes/2.6/

[ChrisGaudreau]

Finally, MongoDB 2.6 lays the foundation for massive improvements to concurrency in MongoDB 2.8, including document-level locking.

This is exciting even if I don't expect it to happen soon.

[zardosht]

TokuMX, which I work on, has document level locking and compression right now.

[anvarik]

With this release aggregation framework got super powerful. Now it returns a cursor. Now we can get the aggregation results and iterate over them. No more 16mb result limitation as well...

[ericcholis]

Agreed, it was annoying to have to use the MapReduce for larger sets.

[jeffdavis]

Can you elaborate for people who don't understand the feature? Is the aggregation result large because of grouping?

[nicklovescode]

I've been using Elasticsearch as a primary database for my new project, which has basically been a good NoSQL db that happens to have great search. However, peripheral tools(performance testing, hosting) have been a bit rough.

How do the two databases compare now. Is search improving in Mongo or is that something they are not really worrying about at the moment.

[endijs]

This is good write-up about what's new with actual numbers. http://devops.com/news/mongodb-2-6-significant-release-mongo... Quote: "MongoDB 2.6 provides more efficient use of network resources; oplog processing is 75% faster; classes of scan, sort, $in and $all performance are significantly improved; and bulk operators for writes improve updates by as much as 5x."

[dkhenry]

Awesome news. I am excited for the aggregation cursor. As much as I love some of the alternatives that are almost ready I still turn to mongo for a vast majority of my deployments. Hopefully it will keep getting better and pushing others to do the same.

[brokentone]

Can someone with more MongoDB experience give me your thoughts on the upgrade difficulty here? Worth doing soon, or waiting for a point release? Does this require a data rebuild/update process (coming from 2.4)?

[Fizzer]

Upgrade notes are here: http://docs.mongodb.org/master/release-notes/2.6-upgrade/

"the upgrade from MongoDB 2.4 to 2.6 is a binary-compatible drop-in upgrade: shut down the mongod instances and replace them with mongod instances running 2.6."

[mason55]

IMO unless you desperately need one of the new features I would hold off a few weeks. With a release this big I'd expect there will be some bugs and wouldn't be surprised to see 2.6.1 shortly.

[arkham]

Authentication is the main thing to be aware of (no data rebuild), but full notes here:

http://docs.mongodb.org/master/release-notes/2.6-upgrade/

And, you have to be on 2.4 first (I know you said you are, but best to make sure for others)

[AdrianRossouw]

So i've been trying to find an the ideal case for mongodb, because I have to teach a nosql database to some people I am mentoring.

I'm leaning heavily towards couchdb though.

http://daemon.co.za/2014/04/when-is-mongodb-the-right-tool

[sync]

Be sure to check out RethinkDB as well, which is pretty much mongo with a MUCH nicer query interface and saner locking.

http://rethinkdb.com/ http://rethinkdb.com/docs/comparison-tables/

[rdtsc]

I would stay with CouchDB. Its web interface if really good for inspecting and debugging what is inside the database. Really good for development.

Also it has a very nice HTTP interface so can talk to it straight from the Web via a proxy.

[arkham]

Well, for teaching purposes, independent of suitability for a use case there are multiple courses available for free here:

http://education.mongodb.com

And, more node.js specific (but also offline capable, and available any time):

http://mongodbschool.io/

[tomsoft]

-> an ideal use case: capture and store unstructured data, typically tweets. Tweets structure is json based, quite complex with many field and substructure. It's incredibly to store and manipulate such data with Mongodb without even knowing all the details of the fields! It's also a good use case beacause mongodb is fairly good at adding data, pretty bad at deleting data.

same with some others document json oriented database (like elastic search), but mongodb is a good compromise in many area, the query language is easy to understand and powerful, the biggest issue being the diffculty to do complex computation and aggreagation: mapreduce help, aggreagation framework helps too, but in this area SQL is generally much faster for instance.

[wilsonfiifi]

Have a look at this: https://github.com/johnwilson/bytengine.

It could have been built with CouchDB however some features such as ad-hoc querying and partial document updates make MongoDB a more compelling choice (albeit prone to some scalability issues until mongodb version 2.8 hopefully lol!).

[id]

While MongoDB has many use cases, it's just perfect if you need to pass over JSON to your JavaScript. Or need JSON output for any other reason.

[arkham]

Some notes on using the shell, and some unforeseen performance changes from the beta: http://comerford.cc/wordpress/2014/03/28/mongodb-2-6-shell-p...

[endijs]

Cursor for aggregate, proper explain for aggregate, index intersection, $redact and other cool operators, Multi* in Geospatial, faster execution and, foundation for document-level locking which should be introduced in MongoDB 2.8. I must say I'm happy with this release.

[hamxiaoz]

Playing with Meteor and mongo recently and have found mongo seems a little bit strange from a transitional SQL point of view, like do I need to embed or reference? Can anyone recommend a good book or source?

[francesca]

http://docs.mongodb.org/manual/tutorial/model-embedded-one-t...

http://docs.mongodb.org/manual/core/data-model-design/

[anvarik]

MongoDB Definitive Guide 2nd ed is pretty good

[wilsonfiifi]

So does this mean document level locking has been implemented or just the foundation for its future implementation has been laid?

I can't hold my breath much longer! :-)

Edit: docs don't make any mention of it but then again they probably haven't updated them yet (fingers crossed!) http://docs.mongodb.org/manual/faq/concurrency/#what-type-of...

[leif]

It means the foundation has been laid. 2.6 included a lot of refactoring and rewriting of some core subsystems, with the apparent goal of eliminating technical debt so they can make more impactful changes in 2.8.

Don't asphyxiate, tokumx has document-level locking right now. http://github.com/Tokutek/mongo

[mdcallag]

I am a big fan of their focus on manageability for sharded databases. I am less of a fan of their db internals that might require you to use many more shards than a more performant engine. More details at http://smalldatum.blogspot.com

[owenversteeg]

The blog post was rather vague about 2.6's "better performance". Are there any concrete numbers?

[Oculus]

The main reason I use MongoDB on Node is the maturity of the Mongoose ORM - I've used Node-ORM 2, BookshelfJS, and SequelizeJS and none of them felt as mature as Mongoose.

[tbarbugli]

How is it possible to have aggregation cursors without crunching the complete data set in advance (aka map/reduce) and still have consistent and correct results?

[tedchs]

Will MongoDB still segfault under certain circumstances?

[ericingram]

I wonder, what does this mean for TokuMX