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Does everyone hate MongoDB?

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Re: Does everyone hate MongoDB?

#91

Post by oracuk »

I've used mongodb for a recent prototype. It was brilliant, I iterated through the data model as I coded.

However, I am now very aware that I have an implicit schema in my code that will be harder to understand in 6 months than a database schema.

I traded fantastic flexibility in initial development against easily maintained longevity.

I suspect I will move to something more relational but have also taken on the need to really understand the trade-offs I'm making. I've started reading Seven Databases in Seven Weeks to fill in some of my gaps.

Re: Does everyone hate MongoDB?

#92

Post by jeremyjh »

pooriaazimi wrote: post #55
diego wrote: post #43

Earlier quoted context omitted.

I like the concept of MongoDB. My main problem (which perhaps is not totally clear from my post, linked in the article) is that there are certain historical conventions about what a database should be. In particular, a database will not have the following default behavior: - return from a write call silently, when the data wasn't written and will not be. If you are going to break conventions on a multi-decade traditi…

I haven't got a 32 bit version of Mongo, but people pointed out in the other thread that 32-bit version of mongod displays a little warning every time you start it saying it can handle only 2GB of data. Can you confirm this ( because I don't have the 32-bit version installed )? It still stinks, especially because it "silently failed after hitting the threshold", but I personally would feel better about 10gen if this…

Yes that is true for me, at least using the 10g binaries for Linux (not the Ubuntu package). You get this warning everytime you start the engine. You'd probably have to look at your logs to see it. It is also referenced in the installation documentation.

Look guys, MongoDB uses a memory-mapped file. How can it be larger than 2GB on a 32-bit system? There should not need to be "warnings everywhere".

Re: Does everyone hate MongoDB?

#93

Post by jeremyjh »

diego wrote: post #83
brown9-2 wrote: post #81

Earlier quoted context omitted.

Do you look at the log anytime something starts successfully and seems to be working? When I first install something new that I'm going to rely on - yes.

How do you know that you're going to rely on it if it's new? I install something new. I kick the tires. It takes a long time until I decide I'm going to rely on it. I'll look at the log at some point, but not necessarily the first time I install something. There are better things to do at that point.

Maybe you should learn something from your failure.

Re: Does everyone hate MongoDB?

#94

Post by base698 »

diego wrote: post #77
werkshy wrote: post #69

Earlier quoted context omitted.

This is true, in the Ubuntu packages this is printed to the default log at /var/log/mongodb/mongodb.log. It is also abundantly clear from the documentation. I struggle to understand how one could deploy a new datastore in production without reading the "getting started" level of documentation or looking in the log at some point. The 2GB 32-bit limit of MongoDB seems like a complete non-issue to me. Wed Sep 19 17:29:2…

Normally people look at logs when things go wrong. Do you look at the log anytime something starts successfully and seems to be working? You must spend lots of time looking at logs. This is a message that MUST be displayed on the console when you install the server for the first time. It's too important. Also, you learn a tool before going into production. I never went into "production" with mongodb. All I did was ex…

Every time I start something I tail -f the relevant log to make sure it starts correctly. Think of it as isolating a possible failure point as a sanity check.

Re: Does everyone hate MongoDB?

#95

Post by Saavedro »

jeremyjh wrote: post #92
pooriaazimi wrote: post #55

Earlier quoted context omitted.

I haven't got a 32 bit version of Mongo, but people pointed out in the other thread that 32-bit version of mongod displays a little warning every time you start it saying it can handle only 2GB of data. Can you confirm this ( because I don't have the 32-bit version installed )? It still stinks, especially because it "silently failed after hitting the threshold", but I personally would feel better about 10gen if this…

Yes that is true for me, at least using the 10g binaries for Linux (not the Ubuntu package). You get this warning everytime you start the engine. You'd probably have to look at your logs to see it. It is also referenced in the installation documentation. Look guys, MongoDB uses a memory-mapped file. How can it be larger than 2GB on a 32-bit system? There should not need to be "warnings everywhere".

I think expecting end-users to know or care about the implementation detail of a memory-mapped file is even sillier than all the other silly expectations floating around this thread.

Re: Does everyone hate MongoDB?

#96

Post by diego »

jeremyjh wrote: post #93
diego wrote: post #83

Earlier quoted context omitted.

How do you know that you're going to rely on it if it's new? I install something new. I kick the tires. It takes a long time until I decide I'm going to rely on it. I'll look at the log at some point, but not necessarily the first time I install something. There are better things to do at that point.

Maybe you should learn something from your failure.

Maybe you should make constructive comments instead of making assumptions about what people learn or don't (or what they know or don't, or what has worked for them or hasn't).

There are some really disrespectful people in this community.

Re: Does everyone hate MongoDB?

#97

Post by mun2mun »

taligent wrote: post #88
23david wrote: post #51

Earlier quoted context omitted.

At our company we have a much bigger MongoDB dataset in production. I can relate well to your comments, since it is the same stuff that I hear from our developers as they defend Mongo after yet another horrific situation. They have a tough time admitting that Mongo is the problem, and instead always find ways to say that it was their fault. This is such a strange thing for me to observe, but I think that it has to do…

> But unfortunately they seemed to spit in the face of DBAs and Ops people a long time ago by proclaiming them to be unnecessary and archaic. WTF ? I have never heard 10gen say anything remotely like this. And it surely hasn't come across in their marketing. I mean seriously. Which developer thinks that in a production environment they are going to be the ones supporting the database ? Nobody. > If MongoDB experts ca…

> But unfortunately they seemed to spit in the face of DBAs and Ops people a long time ago by proclaiming them to be unnecessary and archaic.

>>WTF ? I have never heard 10gen say anything remotely like this.

From the "Ease of use" section of their Philosophy page http://www.mongodb.org/display/DOCS/Philosophy,

   This means that MongoDB works right out of the box, and you can dive right into developing your application, instead of spending a lot of time fine-tuning obscure database configurations.
There goes the indirect jab to the RDBMS DBAs wasting their time.

Re: Does everyone hate MongoDB?

#98

Post by marshray »

jeffdavis wrote: post #87
marshray wrote: post #80

Earlier quoted context omitted.

Isn't one of the defining characteristics of Mongo-like systems that they tend to aggressively favor using RAM to achieve performance? I.e., their strategy is to complete each query as quickly as possible rather than attempt to optimize for fairness of long-running transactions.

I wasn't referring only to long running transactions. Indexes are clearly a way of reducing the working set (at least in a practical sense) but also vital for workloads with many short transactions. I was not criticizing mongo per se, I was criticizing this post and other misguided statements about the working set as it relates to database software.

OK, it just seemed to me that the stated goal of Mongo-like servers was to take some of our accepted notions of the "working set as it relates to database software" and put them up for fresh discussion.

Re: Does everyone hate MongoDB?

#99

Post by Devilboy »

taligent wrote: post #88
23david wrote: post #51

Earlier quoted context omitted.

At our company we have a much bigger MongoDB dataset in production. I can relate well to your comments, since it is the same stuff that I hear from our developers as they defend Mongo after yet another horrific situation. They have a tough time admitting that Mongo is the problem, and instead always find ways to say that it was their fault. This is such a strange thing for me to observe, but I think that it has to do…

> But unfortunately they seemed to spit in the face of DBAs and Ops people a long time ago by proclaiming them to be unnecessary and archaic. WTF ? I have never heard 10gen say anything remotely like this. And it surely hasn't come across in their marketing. I mean seriously. Which developer thinks that in a production environment they are going to be the ones supporting the database ? Nobody. > If MongoDB experts ca…

> The fact that you base your impression of MongoDB based on ZERO evidence just conjecture that the slowness of their site is database related says a lot about you too. There are many other reasons it could equally be: app server, network etc.

Those other things are trivial to fix (e.g. add more app servers) so I too think that it's safe to assume it's probably the data store's fault.

> But it does 'just work' that's the whole point.

Did you read the article?

Re: Does everyone hate MongoDB?

#100

Post by nc17 »

jeremyjh wrote: post #93
diego wrote: post #83

Earlier quoted context omitted.

How do you know that you're going to rely on it if it's new? I install something new. I kick the tires. It takes a long time until I decide I'm going to rely on it. I'll look at the log at some point, but not necessarily the first time I install something. There are better things to do at that point.

Maybe you should learn something from your failure.

You have been a "technology manager" at Bank of America in North Carolina since 1998. Do you try new technologies such as MongoDB professionally? What are your qualifications to make such a vague statement? More importantly, what is the lesson to be learned?
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