Mongo: Mr Right... or Mr Right Now?

Mongo: Mr Right... or Mr Right Now?(blog.scripted.com)

15 points by jbkring 13 years ago | 12 comments

Zak 13 years ago |

I had Mongo lose data.

The box it was hosted on was shut down (possibly uncleanly), and when it came back up, mongod refused to start. I ran mongod --repair and ended up with a running system, but the data was mangled. There were parts of records inside other records and a large amount of data that I just couldn't find. Fortunately, most of it was backed up elsewhere.

I've been told that maybe some other version is more reliable. I've been told I need to configure it properly by hand before I use it. I don't care. This was a trivial single-machine installation and there is one thing any sane database absolutely must do: avoid completely losing all the data that has been stored in it.

dmytton 13 years ago | |

What version was this? 2.0 (which has been out almost a year) has journaling enabled by default which almost always provides complete single server durability for these situations.

Any database can suffer corruption if you shut down the server uncleanly - it depends on the state of the filesystem when it comes back up. That's why you have replication to protect against failure of a single node.

Having run Mongo in production for over 3 years, I've never lost any data despite numerous failure scenarios (including unclean shutdown).

Zak 13 years ago | | |

I believe it was 1.8. I know it wasn't a high-reliability configuration, and it could be that an unclean shutdown was to blame. I do not claim to know objectively how reliable MongoDB is.

I am, however very hesitant to rely on it for anything now, much as I would be hesitant to touch a machine that previously gave me a severe electric shock even though its creator and other users assure me it's safe now.

stuffihavemade 13 years ago |

I don't understand how writing migrations takes "weeks (if not months)". I can see "hours (if not days)". But, you still have a schema and migrations, they just exist in the application layer instead without a clear upgrade path.

jbkring 13 years ago | |

I think you're underestimating just how many times I rethought my schema and refactored my models :)

jbkring 13 years ago |

Anyone else have a good story about Mongo as a speccing tool (as opposed to a long term solution)?

StavrosK 13 years ago | |

I did need a schemaless store for a project I was prototyping, but then I didn't see why I had to install MongoDB just to get a simple schemaless store. So, I wrote Goatfish:

https://github.com/stochastic-technologies/goatfish/

bravura 13 years ago | | |

Wait, you found it too difficult and time-consuming to install software, so instead you wrote software?