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Migrating from MongoDB to Cassandra

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Re: Migrating from MongoDB to Cassandra

#3
When I read posts like this all but confirming MongoDB isn't the great product 10Gen make it out to be, I wonder how the heck MongoDB are still even relevant and then I remind myself of the fact that 10Gen have one of the best marketing and sales teams in the game at the moment.

While MongoDB has improved greatly over previous versions, I can't help but feel if 10Gen put as much effort into improving their product as they do selling it, Mongo would be a force to be reckoned with!

MongoDB is good at some things, but I think most people that try and fail with it fall into one of two camps: 10Gen sold them into it or they bought into the hype without assessing project requirements and ensuring MongoDB was a sensible choice.

Re: Migrating from MongoDB to Cassandra

#4

When I read posts like this all but confirming MongoDB isn't the great product 10Gen make it out to be, I wonder how the heck MongoDB are still even relevant and then I remind myself of the fact that 10Gen have one of the best marketing and sales teams in the game at the moment. While MongoDB has improved greatly over previous versions, I can't help but feel if 10Gen put as much effort into improving their product as…

Like any other NoSQL datastore, things like MongoDB aren't as general purpose as a RDBMS no matter how the marketing and sales teams make them out to be. Cassandra is no different.

People need to read the documentation (say what you will about mongo but 10Gen docs are pretty damn good) more thoroughly before blindly implementing stuff on NoSQL and complaining. (I've been guilty of this in the past.)

Re: Migrating from MongoDB to Cassandra

#6
post #2

read first half of article get spammed leave immediately

Same here.

Author here, sorry about that.

It's not supposed to display on engineering posts but something must have changed/been broken recently. We know you guys aren't interested in marketing content.

Again, sorry about that and thanks for bringing it up.

Re: Migrating from MongoDB to Cassandra

#8

When I read posts like this all but confirming MongoDB isn't the great product 10Gen make it out to be, I wonder how the heck MongoDB are still even relevant and then I remind myself of the fact that 10Gen have one of the best marketing and sales teams in the game at the moment. While MongoDB has improved greatly over previous versions, I can't help but feel if 10Gen put as much effort into improving their product as…

I agree. We're putting a lot of effort into this at Tokutek with TokuMX: http://www.tokutek.com/2014/02/introducing-tokumx-1-4-major-...

Personally, I think the company formerly known as 10gen is doing a lot of good work, particularly with the aggregation framework, but it's orthogonal to the improvements we've made with the storage subsystem.

Re: Migrating from MongoDB to Cassandra

#9

When I read posts like this all but confirming MongoDB isn't the great product 10Gen make it out to be, I wonder how the heck MongoDB are still even relevant and then I remind myself of the fact that 10Gen have one of the best marketing and sales teams in the game at the moment. While MongoDB has improved greatly over previous versions, I can't help but feel if 10Gen put as much effort into improving their product as…

There is one thing MongoDB does spectacularly well - you can feed in arbitrary JSON and get the same JSON back out. (No need to define schemas or play any kind of system/db administrator.) Even the queries have the same "shape" as JSON, so no need for another arbitrary query language.

It will eventually bite you, and bite you hard. But you'll be well into the millions of records before that happens. Developers and products below that number will have very smooth sailing. And some live there permanently. One project I worked on years ago involved a music catalogue. Did you know there are only about 20 million songs?

The main problem is things get very painful as you get bigger, especially for writes. A doubling of write activity can lead to calamitous drops in performance. This is especially bizarre as the data model means they can easily have multiple concurrent writers. Heck having a lock per 2GB data file would quickly help with concurrency.

They have this same "single" approach in other places. For example building an index is single threaded. I did a restore the other day and then had to wait 8 days while it rebuilt indexes. One cpu was pegged but everything else was idle!

It also consumes huge amounts of space - at least double as the same data in JSON. There are known fixes https://jira.mongodb.org/browse/SERVER-164 https://jira.mongodb.org/browse/SERVER-863 (note how popular they are and how many years they have been open!)

I wish they would focus on making better use of the resources available - it should be possible to max out cpu, RAM and I/O.

We've ended up in the same situation as the article, figuring out where to migrate to with Cassandra being the front runner.

Re: Migrating from MongoDB to Cassandra

#10
Viber, one of the largest over the top messaging apps, recently shared their conversion from Mongo to Couchbase. They ended up requiring less than half of the original servers, and better performance.

If you want to see a video of their engineer telling the story, it's available here: http://www.couchbase.com/presentations/couchbase-tlv-2014-co...

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