Introduction to MongoDB • Hacker News Board

Re: Introduction to MongoDB

#11

Post by justinjenkins » Thu, Jan 13, 2011, 2:51 AM UTC

liuliu wrote: post #3

Just wonder who have hosted data that is larger than RAM with MongoDB, and what's the performance characteristics?

You could run into problems but one option to deal with this is to "scale out" to a larger number of machines and shard the data onto each separate machine (with their own RAM) as appose to one or two high RAM machines.

Re: Introduction to MongoDB

#12

Post by [deleted] » Thu, Jan 13, 2011, 3:03 AM UTC

liuliu wrote: post #3

Just wonder who have hosted data that is larger than RAM with MongoDB, and what's the performance characteristics?

[deleted]

Re: Introduction to MongoDB

#13

Post by ethangunderson » Thu, Jan 13, 2011, 5:15 AM UTC

jonburs wrote: post #9

liuliu wrote: post #3

Just wonder who have hosted data that is larger than RAM with MongoDB, and what's the performance characteristics?

This happened to Foursquare, and resulted in a lengthy outage. See http://groups.google.com/group/mongodb-user/browse_thread/th... for the full details (including why recovery took so long).

FWIW, Foursquare's situation was kind of unique. They have a need for all of their data to be in RAM. In most applications, you can define a working set of data. As long as you can keep that working set and indexes in RAM, you'll be fine.

Re: Introduction to MongoDB

#14

Post by throwaway1138 » Fri, Jan 14, 2011, 7:30 AM UTC

justinjenkins wrote: post #11

liuliu wrote: post #3

Just wonder who have hosted data that is larger than RAM with MongoDB, and what's the performance characteristics?

You could run into problems but one option to deal with this is to "scale out" to a larger number of machines and shard the data onto each separate machine (with their own RAM) as appose to one or two high RAM machines.

This bears repeating. Because MongoDB doesn't do joins, sharding is orders of magnitude easier than with an SQL system; if you run out of RAM, shard.

Re: Introduction to MongoDB

#15

Post by saurik » Sun, Jan 16, 2011, 8:02 AM UTC

liuliu wrote: post #3

Just wonder who have hosted data that is larger than RAM with MongoDB, and what's the performance characteristics?

My experience with MongoDB (300GB database; most of which was insert-only, but some large chunk of it was being updated) under constant load was horrible: I would not go back there. I've since spent a lot of time learning more about PostgreSQL's implementation and figuring out how to tweak more performance out of it. At this point I no longer believe there is any benefit to using MongoDB at all.