I cut my teeth on Oracle when I was first getting started in technology. All I did was write ad hoc queries all day long. My next DB heavy job was using SQL Server, where I built an analytics engine to do bootstrapping for sparse datasets. After that I used it to run the back-end data layer for a credit card processing company. I used MySQL at a different finance company that was doing similar things but at a smaller scale. Ever since then, I’ve been using Postgres.

Based on that experience, I’d rank them in this order:

1. Postgres
2. SQL Server
3. Oracle
99. MySQL

Postgres often lags behind the others in features, but the dev team chooses their battles wisely and ends up with better implementations.

Postgres is a real beacon of light in the open source world. Solid community. Many projects claim the benefits of open source, but they are never fully realized. Also, because Postgres is not operated by a freemium model, you always have access to the latest and greatest features. The extensibility is fantastic and well-leveraged by the community. I’ve never experienced a case where Postgres tried to figure out what I was doing and decided to do the wrong thing. Postgres fails early and loudly when there’s a problem with what I’m asking it to do, which is exactly what I want it to do. I don’t ever want to have to second guess the integrity of my data.

I haven’t run explicit benchmarks between any of these databases. But when I do similar things across two different systems, I feel like they are generally on par. But like I said, I can’t prove that with any numbers. There are probably specific work profiles that people can come up with that would show better performance for one platform over the other. But I don’t think there’s a realistic difference in performance in general. Not one that’s big enough to push your decision.

The real moment of revelation though, is when you find out that you can run your preferred programming language inside of Postgres. When you actually get to the point that transformations are outside of what you want to do in SQL, and you can just write a Python function and have it execute inside your database instead of having to do I/O, process the data, and then push it back . . . it is life-changing.

The only reason SQL Server isn’t tied for first place is because of the lack of extensibility and because it’s expensive to use in production. But it is rock solid, and has some nice things that Postgres doesn’t have, like hinting queries. Again, the Postgres community has discussed this, and it may never actually happen, but there are reasonable points as to why not. But it is really handy in SQL Server to be able to guide the query planner on the fly like that. SQL Server has also had solid pub-sub for a long time, though we’re getting that now with this version of Postgres.

I’m not a huge fan of Microsoft in general, but you absolutely have to give them props for their tooling. There is nothing even close to SSMS for any other database system. It is by far the gold standard for a visual interface to you data.

Obviously, if you’re throwing down money, you’re also getting a certain level of support for the product. I’m not convinced this should be a deciding factor between Postgresand SQL Server because, again, the Postgres community is amazing.

I should also point out that there’s a free version of SQL Server that will suffice for the needs of a great many people. It’s features are limited (no pub/sub, and there’s a size limit on your total dataset), but it’s totally functional for a lot of use cases. Even though I use Postgres for everything in production, I will always keep a PC around to run SQL Server for one off things that are just easier to do there.

Oracle is mostly fine. I was so new to everything when I was using it that I probably can’t speak that well to its strengths and weaknesses. Other people who have used it more recently can probably do it better than me. I just can’t for the life of me understand why anyone would pay their prices when SQL Server and Postgres exist, unless it’s for the support contract. And where I’m kind of meh about Microsoft, I’m actively against Oracle and Sun Microsystems. I’m pretty sure that Larry Ellison’s personal model is, “Just go ahead and be evil.” But that’s kind of a tangent and not really all that relevant.

MySQL is a different animal. It has a different design philosophy than the others. It’s more like MongoDB in principle than the others are. It’s main goal is to be friendly to the developer. And to entice you into upgrading to the paid tier.

Which is all fine. But one consequence of that is that it tries really hard to succeed under any circumstance, even if “success” means corrupting or losing your data. So it fails rarely, late, and quietly under certain conditions.

For that reason, I don’t think of it as even being in the same category as the other three. As in, it would never be an option for me, similar to MongoDB. I want my dev tools and programming languages to be focused on the developer. And I want my data store to be focused on my data. I think that this is a fundamental and deadly flaw with MySQL.

Different use cases have different requirement though, so your mileage will vary. I’m an incredible pedant about data integrity because the work I do requires it. There are legitimate cases where it just doesn’t matter all that much.

But in terms of feature parity and performance, they are all pretty close in general terms. Each will have specific cases that they really excel at and have been optimized for.