| copied from my blog: @kristina for some reason wordpress wanted me to moderate your post so sorry for the delay in it showing up. >> Whoopsy, got your emphasis wrong there ….. Seriously, though, this “unchecked” type
>> of write is just supposed to be for stuff like analytics or sensor data, when you’re getting
>> a zillion a second and don’t really care some get lost if the server crashes. did the default change? the last time i attempted to a concurrent performance test this was one of the barriers i hit. my issue isn’t that you include this feature, it’s that it’s the default, i certainly believe there is a use case for it i just think it’s harmful as a default. >> Since CouchDB is “not a competitor” to MongoDB, it’s nice of you to put all this time
>> into a public service. haha, that’s funny. i regularly use non-CouchDB databases and I get along great with all the people from other databases at conferences. even if i did feel like we were competing, i wouldn’t care. this post really is about reliability issues i don’t think your users are fully aware of and i honestly hope that you fix. >> fsyncs are configurable. You can fsync once a second, never, or after every single insert,
>> remove, and update if you wish. that’s really good to hear. have you optimized for a “group commit” yet? >> This is because you assume you’ll run it on single server. MongoDB’s documentation
>> clearly, repeatedly, and earnestly tells people to run MongoDB on multiple servers. I responded earlier to the complexity of actually keeping something available that depends on this. so i won’t cover it again. >> That’s not to say that things never go wrong, MongoDB is definitely not perfect and has
>> lots of room for improvement. I hope that users with questions and problems will
>> contact us on the list, our wiki, the bug tracker, or IRC (or, heck, write a snarky blog
>> post). Anything to contact the community and let us try to help. I wish every person
>> who tried MongoDB had a great experience with it. You make it sounds like this is all just a matter of bugs, it’s not, and i find blaming it on users who don’t use JIRA or get on IRC a little distasteful. these issues are architectural and until you do something append-only they aren’t going to go away. someone mentioned earlier that you plan to do an append-only transaction log, if that’s accurate then it’s fantastic news. |
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> haha, that’s funny. i regularly use non-CouchDB databases and I get along great with > all the people from other databases at conferences.
Oh, I tend to bite people when I find out they use another database . Maybe I should stop that?
> even if i did feel like we were competing, i wouldn’t care. this post really is about > reliability issues i don’t think your users are fully aware of and i honestly hope that > you fix.
You must be thrilled to learn that single server durability is coming. I look forward to a followup post extolling MongoDB’s virtues this fall.
> I responded earlier to the complexity of actually keeping something available that > depends on [multiple servers]. so i won’t cover it again.
Yes, it is a difficult, but not unsolvable, problem. Mongo’s made a bunch of tradeoffs in the awesome vs. easy to program area. For instance, remember last year when CouchDB was saying MongoDB sucked because of its lack of concurrency? That it was too complicated to do concurrency in C++ and that Erlang was the way? Well, now Mongo has concurrency, so on to the next “must have” thing.
>You make it sounds like this is all just a matter of bugs, it’s not, and i find blaming > it on users who don’t use JIRA or get on IRC a little distasteful.
People discuss everything from bugs to architecture to lunch on our various forums. I was trying to say, possibly badly, that we have a lot of ways for people with questions, problems, and suggestions to reach out.
Eliminating the methods I outlined, I’m not sure how people with suggestions could reach the developers, other than telepathy.
Also, the user you cite is far from typical. It sucks that some people don’t like Mongo, but there’s are a lot more out there from those who do: http://codeascraft.etsy.com/2010/07/03/mongodb-at-etsy-part-..., http://blog.eventbrite.com/guest-post-why-you-should-track-p..., http://blog.wordnik.com/what-has-technology-done-for-words-l..., http://www.engineyard.com/blog/2009/mongodb-a-light-in-the-d... and so on.