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There's a lot of FUD going around when it comes to MongoDB write durability. Please read the manual. Mongo lets the user decide whether or not to wait for fsyn

by reqres 11y ago

There's a lot of FUD going around when it comes to MongoDB write durability. Please read the manual. Mongo lets the user decide whether or not to wait for fsync when writing to an individual node. This is not the default configuration. If you want it, you can enable it. You may complain that Mongo has bad defaults for your particular use case. It continues to have bad defaults to this day. Saying Mongodb is unable to acknowledge writes to disk is pure FUD. Let the downvotes ensue.

justicezyx 11y ago
That's certainly a downgrade on the standard. Durability is a must not an option. The statement may not be friendly, but it is not down-vote-justifiable.
eloff 11y ago
It's like if MySQL shipped with libeatmydata configured by default. The defaults should be safe. Mongo made not just a bad choice, but a really idiotic decision to make their default configuration non durable.
- outworlder 11y ago
  Well, MySQL does ship like that. Only instead of not saving your data, it will mangle it in an effort to insert it in the database somehow.
- omni 11y ago
  > The defaults should be safe. That's one opinion fitting one set of use cases. There are plenty of use cases where speed is more important than durability. Hell, Redis default configs don't enable the append-only log, but you don't see the HN hate train jumping all over Redis. This is because Redis use cases typically don't require that level of durability. edit for source: cmd+f for "appendonly" https://raw.githubusercontent.com/antirez/redis/2.8/redis.conf https://raw.githubusercontent.com/antirez/redis/2.8/redis.co...
  - eloff 11y ago
    Redis doesn't market itself as a general purpose database, more as an advanced memcached, which is why those make sense. People who value performance over durability can of course change the setting, being aware of what they are getting into. That's very different from someone who doesn't realize that just because his database seems to save his data doesn't mean it won't eat it tomorrow because he didn't know to change the configuration. I stand by my judgment of hopelessly stupid.
deleted 11y ago
[deleted]
rdtsc 11y ago
> There's a lot of FUD going around when it comes to MongoDB write durability. Please read the manual. Mongo lets the user decide whether or not to wait for fsync when writing to an individual node. [...] It continues to have bad defaults to this day. Saying Mongodb is unable to acknowledge writes to disk is pure FUD. > Let the downvotes ensue. There's a lot of FUD going around when it comes to Ford Model X car not having brakes enabled. Please read the manual. Ford Model X lets the user decide whether or not to enable brakes or not. [...] It continues to have bad defaults to this day. Saying Ford Model X is unable to brake is pure FUD. Let the downvotes ensue.
- Kudos 11y ago
  Oh great, an analogy. Now we can start debating its subtleties instead of discussing the matter at hand.
- threeseed 11y ago
  You are just being childish. Firstly MongoDB's write durability was set to use the safest option on all of the drivers at the time. So your point makes no sense. And secondly we aren't ignorant users of the system. We are highly technical and as such your analogy again makes no sense.
brazzledazzle 11y ago
>Let the downvotes ensue. Can we not have this reddit-ism take hold?
takeda 11y ago
It loses data even with WriteConcern.MAJORITY[1]. Emin Gün Sirer summarized[2] it best: > WriteConcern is at least well-named: it corresponds to "how concerned would you be if we lost your data?" and the potential answers are "not at all!", "be my guest", and "well, look like you made an effort, but it's ok if you drop it." [1] https://aphyr.com/posts/284-call-me-maybe-mongodb https://aphyr.com/posts/284-call-me-maybe-mongodb [2] http://hackingdistributed.com/2013/01/29/mongo-ft/ http://hackingdistributed.com/2013/01/29/mongo-ft/

by reqres 11y ago

justicezyx 11y ago

That's certainly a downgrade on the standard. Durability is a must not an option. The statement may not be friendly, but it is not down-vote-justifiable.

eloff 11y ago

It's like if MySQL shipped with libeatmydata configured by default. The defaults should be safe. Mongo made not just a bad choice, but a really idiotic decision to make their default configuration non durable.

outworlder 11y ago
Well, MySQL does ship like that. Only instead of not saving your data, it will mangle it in an effort to insert it in the database somehow.
omni 11y ago
> The defaults should be safe. That's one opinion fitting one set of use cases. There are plenty of use cases where speed is more important than durability. Hell, Redis default configs don't enable the append-only log, but you don't see the HN hate train jumping all over Redis. This is because Redis use cases typically don't require that level of durability. edit for source: cmd+f for "appendonly" https://raw.githubusercontent.com/antirez/redis/2.8/redis.conf https://raw.githubusercontent.com/antirez/redis/2.8/redis.co...
- eloff 11y ago
  Redis doesn't market itself as a general purpose database, more as an advanced memcached, which is why those make sense. People who value performance over durability can of course change the setting, being aware of what they are getting into. That's very different from someone who doesn't realize that just because his database seems to save his data doesn't mean it won't eat it tomorrow because he didn't know to change the configuration. I stand by my judgment of hopelessly stupid.

deleted 11y ago

[deleted]

rdtsc 11y ago

> There's a lot of FUD going around when it comes to MongoDB write durability. Please read the manual. Mongo lets the user decide whether or not to wait for fsync when writing to an individual node. [...] It continues to have bad defaults to this day. Saying Mongodb is unable to acknowledge writes to disk is pure FUD. > Let the downvotes ensue. There's a lot of FUD going around when it comes to Ford Model X car not having brakes enabled. Please read the manual. Ford Model X lets the user decide whether or not to enable brakes or not. [...] It continues to have bad defaults to this day. Saying Ford Model X is unable to brake is pure FUD. Let the downvotes ensue.

Kudos 11y ago
Oh great, an analogy. Now we can start debating its subtleties instead of discussing the matter at hand.
threeseed 11y ago
You are just being childish. Firstly MongoDB's write durability was set to use the safest option on all of the drivers at the time. So your point makes no sense. And secondly we aren't ignorant users of the system. We are highly technical and as such your analogy again makes no sense.

brazzledazzle 11y ago

>Let the downvotes ensue. Can we not have this reddit-ism take hold?

takeda 11y ago

It loses data even with WriteConcern.MAJORITY[1]. Emin Gün Sirer summarized[2] it best: > WriteConcern is at least well-named: it corresponds to "how concerned would you be if we lost your data?" and the potential answers are "not at all!", "be my guest", and "well, look like you made an effort, but it's ok if you drop it." [1] https://aphyr.com/posts/284-call-me-maybe-mongodb https://aphyr.com/posts/284-call-me-maybe-mongodb [2] http://hackingdistributed.com/2013/01/29/mongo-ft/ http://hackingdistributed.com/2013/01/29/mongo-ft/