[uberduper]

MongoDB moved on from mmap at version ~3.6. WiredTiger can be configured to fsync every commit. Enjoy trying MongoDB!

PS: I really miss working with mongodb. It's been almost 7 years since I last used it. I'm surprised I don't see it mentioned very often anymore.

[AtlasBarfed]

Last I heard of MongoDB it was getting utterly buried by the Jepsen guy, and for anyone that follows distributed systems at some technical level, that is damning. He finds stuff wrong with everything, but that one was particularly damning.

MongoDB has always seemed to place write consistency secondary to other priorities (mostly sales / read / features) which is frankly a crap way to do a database, much less a distributed one. And I am so sick of MongoDB basically saying "no it's fixed in the new version" which is always a major red flag.

Right now it's getting its lunch eaten by Postgres's document interface from what I can tell.

[threeseed]

a) Every distributed database has had serious issues with Jepsen.

b) MongoDB has been growing revenue ~40% year on year for the last few years.

c) PostgreSQL is only a serious competitor for MongoDB if you have small datasets. After all these years PostgresSQL still is ridiculously poor when it comes to clustering, replication etc. Everyone's solution of "just buy a bigger instance" is just laughable.

[KptMarchewa]

Growing revenue of a owner company as a argument for database? We have an Oracle fan here.

[AtlasBarfed]

Jepsen does find stuff with everything. Thus you have to know what is being discussed is serious and blatantly bad, or just the usual "wow distributed is hard".

Which is why his papers are so great.

But the MongoDB one was "wow this is bad".

[threeseed]

Every distributed database has been "wow this is bad".

I assume you have an example of one that wasn't ?

[AtlasBarfed]

"MongoDB’s default level of write concern was (and remains) acknowledgement by a single node, which means MongoDB may lose data by default."

Cassandra doesn't do that, consistency level is fundamental to the documentation and user guide. That is AWFUL.

"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.

"

That is fraud. That is clownshow. Enjoy your increasing revenue.

[threeseed]

The default write concern for the last 2 years has been majority.

And single node is a perfectly fine default for most use cases.

After all Cassandra's default consistency level is 1.

[doctor_eval]

Although it was some time ago and I may be misremembering, I seem to recall reading the Jepsen article on RedPanda and thinking that it (and Postgresql) were among the better reports.

Certainly, not all Jepsen reports are all that bad, and tbh I'm at leaast as interested in the way the vendors respond (some of which have been terrible).