> why no run your own DB?

Running your own DB introduces tons of risk that just isn't worth saving a couple bucks (until you're at the scale that it is).

> That said, Mongo is a poor choice for any app ever written.

Sorry, that just isn't true. It works great for us, and is the 4th most popular database by usage (and growing). https://insights.stackoverflow.com/survey/2018#technology-da...

Using mongo as a DB adds more risk then using self hosted Postgres or MySQL. You can use provider hosted Postgres or MySQL for less money and a better product.

McDonalds is very popular, doesn’t mean it’s good food. Be wary the metrics of success you use.

Can you quantify anything? How does mongo add more risk? How is mysql a better product. It doesn't seem like you're saying anything.

How can it be your largest expense but running your own db would save only a couple of bucks?

We don't spend much :)

Just because it works doesn’t mean it wasn’t a poor choice still.

You could have said the same thing about storing your passwords in plain text.

Bit of a disingenuous statistic. It’s popularity is down to being the default choice for people learning the MEAN/MERN stack. Which is a large number of people currently teaching themselves web dev and goes hand in hand with the rise in popularity of Javascript. It’s got little to do with wether people need a document store or wether it’s good at that job, 99% of the time it’s being used to dump relational data.

1. Only people who have never run their own database at scale make flippant "just run your own DB" statements. Because it is a difficult job to do right e.g. testing of backup/restore, clustering, monitoring etc. Especially if you are a growing startup.

2. MongoDB is a great database if you have a data model that suits it. Problem is a lot of people have treated like it was relational. And operationally it's far simpler than most systems out there.

I run my DB at scale right now. About 2h of work a month. Hint I don’t use mongo.

Both AWS and GCE offer hosted Postgres for less than third party hosted mongo.

What model is good for mango? Postgres has jsonb. Cassandra has large scale data. Mongo is in a weird spot in the middle that isn’t great at anything.

MongoDB is a document store which has much better querying and update capabilities than PostgreSQL's JSONB/HStore. It's also probably an order of magnitude faster when it comes to updates.

Not sure why you brought up Cassandra it is not a document store and completely irrelevant to this discussion.

Postgres used to benchmark faster than MongoDB as a document store when compared to MongoDB running with a reasonable reliability setting. Not sure if that has changed in the last few years though - Mongo has improved a bit, and Postgres is getting faster on each release.

Let the tired old irrelevant Mongo-flamewars begin!

As much as I agree, the arguments are a bit tired, I think the criticism can be useful.

There's a tendency in web development towards using well known stacks, and some of them are quite poor choices for most projects. MongoDB features heavily in these stacks despite relational databases being a better fit most of the time, possibly because there's less visibility of alternatives in the JS community.

Do you think the OP is storing documents? I will put cash money they are doing something like the MEAN stack and storing relational or semi relational data in Mongo. Not many startups spend the majority of their storage storing documents.