MongoDB 2.6 Released

http://blog.mongodb.org/post/82092813806/mongodb-2-6-our-biggest-release-ever

by francesca • 12 years ago

143 117 12 years ago

blog.mongodb.org

lazyloop• 12 years ago

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

arkham6• 12 years ago

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...

the1• 12 years ago

mongodb is the best database in the whole wide world at the moment. I encourage everyone to jump in mongodb for agile web scale development with full big data capability.

JulianMorrison• 12 years ago

Oh? How is it better than rethinkdb (at the same job)?

bgilroy26• 12 years ago

the1 won't tell you. S/he's teasing.

zeroDivisible• 12 years ago

Well, I think I must disagree with you in here.

I'm sure that it is a viable choice for some use cases, it's just that I didn't found a use case for it yet.

Being able to choose from PostgreSQL, Redis, Cassandra, heck, even ElasticSearch made me always choose one of those over MongoDB, at least for the problems which I had been trying to solve.

mutex0074• 12 years ago

By the way if you are looking for all the above functionality provided by all the DBMS you mentioned in a single DBMS instance, you can check out amisaserver.com. Polygot persistence is just another fad.

orthecreedence• 12 years ago

Don't forget RethinkDB. Very good general-purpose document store that supports joins and has an excellent query language (no DB write lock either!)

16bytes• 12 years ago

I truely can not tell if this comment is meant to be flamebait, buzzword-laden sarcasm, or NoSQL fanboy-ist.

calebm• 12 years ago

Obvious sarcasm (https://www.youtube.com/watch?v=b2F-DItXtZs)

wilsonfiifi5• 12 years ago

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...

leif4• 12 years ago

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

danielrpa• 12 years ago

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• 12 years ago

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.

arkham6• 12 years ago

It doesn't use mmap for locking though - and in any case one database is already multiple files (2GB max). There are internal data structures used by MongoDB and the database itself takes care of locking, mmap just gets the data into memory.

AlisdairO2• 12 years ago

mmap does complicate things. A traditional database often works using write ahead logs. The log holds changes made to the database over time - so when you want to write a change to your DB, you put 'I'm changing value x.y to 50' in your WAL. Sometime later the actual data pages holding the modified x data structure can be written out to disk. If you have a crash before the data pages get written out, you can 'replay' your WAL file to redo all the lost changes.

Unfortunately, a central requirement of a write ahead log is that the data pages must not get written before the WAL. If that were to occur, and there were a crash, the system wouldn't know that it had to undo the changes to the data pages, leaving you with corrupt data. mmap generally doesn't provide the ability to pin your dirty pages in memory - they're subject to getting flushed any time the system is under memory pressure - so it makes logging a lot more complicated to get right.

bashcoder2• 12 years ago

Yes, and an important limitation stems from this as well.

For a tool like Redis, it's fairly easy for me to accept the limitation that my data size can't exceed available RAM.

But for an indexed document store with full-text query capabilities, it's a lot harder to for me to accept that limitation.

Kiro• 12 years ago

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

mikegioia2• 12 years ago

High volume of writes

sigzero• 12 years ago

"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.

portmanteaufu• 12 years ago

It was about a year between the first release of 2.4 and the 2.6 release. Should we expect another full year for 2.8?

disbelief• 12 years ago

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.

rogerbinns5• 12 years ago

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.)

citruspi• 12 years ago

I believe the 2 GB database limit is only applicable to 32-bit instances[0].

[0] http://blog.mongodb.org/post/137788967/32-bit-limitations

anvarik3• 12 years ago

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• 12 years ago

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

jeffdavis• 12 years ago

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

anvarik3• 12 years ago

Well, aggregation in MongoDB allows you to write sql like queries, and before 2.6 if aggregated result was > 16mb it was throwing an error, but now it gives you a cursor. Now you can fetch the results and send to another collection. For an example aggregation query in mongo have a look here: http://docs.mongodb.org/manual/tutorial/aggregation-zip-code...

ericingram• 12 years ago

I wonder, what does this mean for TokuMX

wilsonfiifi5• 12 years ago

Am glad someone has brought up TokuMX. Tell me, have you used it in production yet?

I wonder why 10gen hasn't made any official comment on the work the folks at Tokutek are doing to enhance Mongodb's features.

mason552• 12 years ago

I wonder why 10gen hasn't made any official comment on the work the folks at Tokutek are doing to enhance Mongodb's features.

Why would they comment? What would they say? Toku is basically trying to steal MongoDB's customers, they even use the same basic pricing model.

leif4• 12 years ago

It means we have some auditing and backporting work ahead of us in the next few months.

tedchs2• 12 years ago

Will MongoDB still segfault under certain circumstances?

outside1234• 12 years ago

Everything will segfault under certain circumstances.

saurik• 12 years ago

The only reasonable assumption is circumstances that do not involve hardware failure, the binary being compiled incorrectly, the source code being modified or replaced by someone downstream, the libraries it is using being corrupt or having been replaced by ABI-incompatible variants... none of these are reasonable circumstances; one would then further assume that the person posting has run into reasonable circumstances where MongoDB often crashes, which is not a stretch given the number of bugs that are filed against it that talk about this kind of issue.

https://www.google.com/search?q=site:jira.mongodb.org+mongod...

rdtsc2• 12 years ago

Have never seen my python server segfault.

ChrisGaudreau• 12 years ago

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.

zardosht3• 12 years ago

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

int643• 12 years ago

trying amisaserver found it somewhere in the comments below. claims to have MVCC.

rainmaking2• 12 years ago

I have never understood how the definition of "Document Database" is different from "File System".

decentrality• 12 years ago

It's very close to JSON objects. In fact, it uses JSON/BSON. So it's Hashes of data structures, which MongoDB makes accessible quickly, like a file system must be.

You can also use GridFS to store files in the document database, which actually breaks files into chunks and stores them in collections, also just like a FAT table.

herge2• 12 years ago

Really? Have you ever tried to search for specific content in structured documents on a filesystem?

leccine• 12 years ago

I have, and found what I was looking for. What am I doing wrong?

rainmaking2• 12 years ago

You are referring to using an index, correct? Because grep is absolutely, madly efficient for a doing a full search.

The index portion of a file system are called files and directories.

Several file names can refer to the same data. Those are called hard links.

So with hard links, I can refer to a Foo by their related Bar.

/foo/foo1 /foo/foo2 /foo/by_bar/bar1 /foo/by_bar/bar2 /foo/by_bar/bar3 /bar/bar1 /bar/bar2 /bar/bar3 /bar/by_foo/foo1 /bar/by_foo/foo2

If I am not mistaken, this accurately describes the limits of MongoDB in terms of mapping relations. I'm not a Mongo expert because no one could convince me otherwise to date, somebody correct me?

mutex0074• 12 years ago

In the case of MongoDB, dump a blob called BSON which itself can be larger than the JSON itself. Paradoxically this is touted as a space efficient binary serialization you then read it back using an index or something.

hamxiaoz• 12 years ago

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?

anvarik3• 12 years ago

MongoDB Definitive Guide 2nd ed is pretty good

francesca• 12 years ago

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

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

dkhenry• 12 years ago

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.

endijs2• 12 years ago

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.

AdrianRossouw5• 12 years ago

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

wilsonfiifi5• 12 years ago

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!).

AdrianRossouw5• 12 years ago

thanks! I'll take a look at it.

I use elasticsearch for adhoc querying : http://daemon.co.za/2012/05/elasticsearch-5-minutes/

And couchdb does have atomic in-place updates, http://wiki.apache.org/couchdb/Document_Update_Handlers

I used the latter recently to track the last view-time on images, as well as to build a schema migration routine in like 100 lines of code.

edit fixed link

id• 12 years ago

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.

AdrianRossouw5• 12 years ago

I can't see how that's a defining feature for it, because couchdb and others also do this really really well. Most of the time you don't even need db drivers, because couchdb is just a REST server.

zaidf• 12 years ago

On the list of reasons to use MongoDB, shouldn't being able to pass over JSON be at the bottom of the list given how trivial it is to pass a mysql row as a json array?

arkham6• 12 years ago

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/

AdrianRossouw5• 12 years ago

thanks.

the latter is especially useful. I'll pass it along to people for extra reference.

rdtsc2• 12 years ago

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.

sync• 12 years ago

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/

AdrianRossouw5• 12 years ago

I've had it recommended a few times now. I'll add it onto the pile =)

sandstrom• 12 years ago

I can also recommend checking out rethinkdb. It feels like MongoDB but without many of the downsides.

Not saying MongoDB is bad (I've used Mongodb and like it), but much of their API-design is quirky/bad, locking is an issue and mmap feels weird too.

tomsoft• 12 years ago

-> 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.

brokentone• 12 years ago

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• 12 years ago

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."

arkham6• 12 years ago

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)

mason552• 12 years ago

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.

colechristensen• 12 years ago

This is always best practice for anything important unless you find your life is dull and bereft of emergency.

doug1001• 12 years ago

an old one, but the circumstances arise so often (app updates) and the consequences so severe (shark attack!) that it's probably worth posting:

https://xkcd.com/349/

owenversteeg• 12 years ago

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

fiatmoney• 12 years ago

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.

Oculus• 12 years ago

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.

bpicolo• 12 years ago

Mongoose is definitely a pleasure to work with, regardless of MongoDB faults. Well-designed.

woah• 12 years ago

Great ORM. Has undoubtedly made MongoDB millions by now.

tbarbugli• 12 years ago

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?

nicklovescode• 12 years ago

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.

int643• 12 years ago

if you are looking for a nosql dbms as a service which consumes json and supports SQL and search, you could try amisaserver

ddorian434• 12 years ago

have you seen the pricing? it's insane

arkham6• 12 years ago

2.4 introduced text indexes for full text search as a beta, and 2.6 finishes the job of fully integrating them into the product - they are fully supported with the new release (including in the aggregation framework).

In terms of how they compare, I'm not familiar enough with Elasticsearch to comment, but for basic test searching needs, the implementation in MongoDB is pretty decent. More here:

http://docs.mongodb.org/manual/core/index-text/#text-search

endijs2• 12 years ago

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."

rogerbinns5• 12 years ago

Mongo haven't updated their feeds for Ubuntu. I wonder how long they will take to do so?

rogerbinns5• 12 years ago

They have now. However 2.6 uses different package names, configuration file name, log file etc. It is generally mongod instead of the earlier mongodb (eg before it was /etc/mongodb.conf and is now /etc/mongod.conf).

This means no automatic upgrades to 2.6, and sysadmin action to correct config file name etc.

mdcallag• 12 years ago

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

MongoDB 2.6 Released

Related Stories