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Jepsen Disputes MongoDB's Data Consistency Claims

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Re: Jepsen Disputes MongoDB's Data Consistency Claims

#221

Post by madhadron »

Diederich wrote: post #104
madhadron wrote: post #27

In the circles I run in, MongoDB is regarded as a joke and the company behind it as basically duplicitous. For example, they still list Facebook as their first user of MongoDB on their website, for example, but there is no MongoDB use in Facebook hasn't been for years (it came in only via a startup acquisition). I had the misfortune to use MongoDB at a previous job. The replication protocol wasn't atomic. You would f…

> but there is no MongoDB use in Facebook hasn't been for years Are you sure?

Until very recently I worked there, and at once point I dug quite deeply into the company to see if I could find if it was still in use. I couldn't find documents referencing its present existence, packages to install it, or anything else, so I'm pretty certain that it's not in use.

Re: Jepsen Disputes MongoDB's Data Consistency Claims

#222

Post by infogulch »

jen20 wrote: post #177
kyllo wrote: post #128

Earlier quoted context omitted.

I was floored by this comment yesterday from one of their Developer Relations people: > Did any of you actually read the article? We are passing the Jepsen test suite and it was back in 2017 already. So, no, MongoDB is not losing anything if you know what you are doing. https://twitter.com/MBeugnet/status/1253622755049734150?s=20 Can you imagine saying the phrase "if you know what you are doing," in public, to your u…

Firstly let me point out that this response is neither intended as a defence of MongoDB defaults which are atrocious, or of the company, who are arguably duplicitous. However I can _quite easily_ see how a non-native English speaker could use the phrase “if you know what you are doing” to mean “if you are careful”.

Even so, they're just implicitly admitting to the very accusations that they are defending. If "running it right" is so insufficiently defined that jespen cannot figure out how to set it up, maybe your product just doesn't actually offer consistency. Sure, you're conceding at a different abstraction level, but it still means that you're failing to solve the problem of consistency for businesses that that want to solve it with your product.

He just replaced "cannot consistently synchronize data" with "cannot consistently deploy a system that can consistently synchronize data". But what's the difference between those statements to people that need to solve that problem? None.

Re: Jepsen Disputes MongoDB's Data Consistency Claims

#223

Post by Carpetsmoker »

Thaxll wrote: post #46
naked-ferret wrote: post #5

From the jepsen report: """ Curiously, MongoDB omitted any mention of these findings in their MongoDB and Jepsen page. Instead, that page discusses only passing results, makes no mention of read or write concern, buries the actual report in a footnote, and goes on to claim: > MongoDB offers among the strongest data consistency, correctness, and safety guarantees of any database available today. We encourage MongoDB t…

MySQL and PG are not truly consistent per default, they don't fsync every writes. MongoDB explains that pretty well: https://www.mongodb.com/faq and https://docs.mongodb.com/manual/core/causal-consistency-read...

I don't know if this is true or not, but it's besides the point; MongoDB omitted various failings from the Jepsen report to make their product look better than it actually is. This is not only unethical, but may also be illegal in various jurisdictions under false advertising laws.

Whatever failings MySQL or PostgreSQL may or may not have are not important at all here.

Re: Jepsen Disputes MongoDB's Data Consistency Claims

#224

Post by Carpetsmoker »

takeda wrote: post #18
lostcolony wrote: post #10

Earlier quoted context omitted.

I appreciate your optimism in thinking that most (all?) people reaching for distributed systems actually know enough in the space to evaluate such claims.

Agree, and the "Mongo and Jepsen" page isn't targeting distributed systems experts, most of them know to stay away, because even if there are things that mongo does right, other systems do it better.

What other systems would you recommend?

Re: Jepsen Disputes MongoDB's Data Consistency Claims

#226

Post by ianamartin »

jb3689 wrote: post #171
therealdrag0 wrote: post #127

How is Cassandra as an alternative to MongoDB?

I mean, they are completely different. MongoDB is more-or-less a traditional RDBMS with automated failover and trying to staple on more advanced features. Cassandra is a masterless DynamoDB-ish database with features like hinted handoffs. You really need to know how consistency and distributed systems work if you're looking to pick Cassandra. It's a great implementation, you just can't compare it to MySQL/Postgres/et…

wat.

I hope this is a joke.

Re: Jepsen Disputes MongoDB's Data Consistency Claims

#227

Post by threeseed »

therealdrag0 wrote: post #127

How is Cassandra as an alternative to MongoDB?

It's not.

The only thing similar about the two is that they both store data and have the letter D in their name. Otherwise they are completely different, Cassandra being a BigTable style database and MongoDB being a document one.

Re: Jepsen Disputes MongoDB's Data Consistency Claims

#228

Post by square_usual »

kipply wrote: post #189
madhadron wrote: post #27

In the circles I run in, MongoDB is regarded as a joke and the company behind it as basically duplicitous. For example, they still list Facebook as their first user of MongoDB on their website, for example, but there is no MongoDB use in Facebook hasn't been for years (it came in only via a startup acquisition). I had the misfortune to use MongoDB at a previous job. The replication protocol wasn't atomic. You would f…

Tangentially related their sales strategy is questionable. As an intern at Shopify, I got an email from MongoDB asking us to switch. Shopify was 10 years old the time. Plus several coworkers would also receive similar emails two years later (and some in between of course). I have a shirt from MemSQL that says "Friends don't let friends NoSQL" and I wear it proudly.

If their sales team is sending emails to interns, their strategy is very questionable indeed.

Re: Jepsen Disputes MongoDB's Data Consistency Claims

#229

Post by callalex »

mathattack wrote: post #197
madhadron wrote: post #27

In the circles I run in, MongoDB is regarded as a joke and the company behind it as basically duplicitous. For example, they still list Facebook as their first user of MongoDB on their website, for example, but there is no MongoDB use in Facebook hasn't been for years (it came in only via a startup acquisition). I had the misfortune to use MongoDB at a previous job. The replication protocol wasn't atomic. You would f…

I have found their salespeople to be the most sleazy and unethical of any that I’ve worked with. Much worse than all the other database vendors combined.

I know they are trying to beat Oracle in this sector, but I didn’t realize they meant it like this!

Re: Jepsen Disputes MongoDB's Data Consistency Claims

#230

Post by balfirevic »

pier25 wrote: post #205

Anyone has a recommendation for a NoSQL database? https://news.ycombinator.com/item?id=23253870 (not Mongo obviously)

This question sounded familiar - turns out I replied to it in another thread: https://news.ycombinator.com/item?id=23286054

To repeat my (non)answer:

There is no way to recommend NoSQL database without knowing what you need it for because NoSQL databases are highly specialized systems. If you need general-purpose database use an SQL one.

It's kind of a weird question, now that I think about it. Why would anyone seek out a database based on what it doesn't have?

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