I'm thinking of Redis in particular. If you're using it as incredibly fast but not critical storage, it's trivial to set up and it ~never crashes or requires maintenance. It creates no headaches, and in exchange gives me a k/v store that I can thrash without worrying about performance (I know it's fast), downstream impact (am I slowing down critical-path SQL queries), etc. Especially in the age of LLMs, which I've found to be great at devops-type tasks, I feel slightly less compelled to simplify my stack.
I'm far more hesitant to throw a more formal MQ in the mix though... mostly from experience in that a lot of mid level ("senior") developers don't really understand queues very well at all. Even if conceptually, using tables for queues is more complex.
That said, I will use PG for workflows similar to K/V, Document (JSONB) and other structures over reaching for say MongoDB, etc.
It's not that it's necessarily complex. But if you don't need it, don't use it. The business could use your time elsewhere
For a persistent store.. sure... but that's true for PostgreSQL as well, which has some pretty painful major version migrations by comparison to other options.
A better response to my comment could have been "just let it go" or something. ₍₍(˶>ᗜ<˶)⁾⁾
An example of a table that would benefit from this would be rate-limits / concurrency-limits, which are commonly implemented using Redis instead of Postgres.
What I don't want is long running unrelated transactions keeping old tuples alive just it case they're needed. My third suggestion where transactions attempting to read old versions fail is probably better than the first two where isolation gets silently downgraded, since it avoid that problem.
This has two implications:
1) make sure if you use Postgres for anything beyond core rdbms functionality that there is no dependency between the two, so you can rip out the additional functionality and move to a different platform when you end up needing to reduce the load on your db server
2) if using Postgres for non-essentials complicates your db backup workflow, risks the data integrity, makes it difficult to maintain or upgrade your Postgres instance (eg you have to wait months or years for compatibility with newer Postgres versions), or loads relatively shoddy or unstable code into the beating heart of your application, then you should either use a different Postgres server/install/container for these ancillary services or bite the bullet and introduce an alternative dependency, depending on which makes more sense.
> only after pushing Postgres to its limits, documenting why it was insufficient, and accepting the operational cost of the alternative
I love Postgres as a DB but, really, this is ridiculous. No doubt these extensions can do the job well-enough but you might as well invest in learning the right tool for the problem from the start, when the stakes are still pretty low. Why wait until, ahem, Postgres is pushed to the limit before you spin up a Redis cluster?
You don't get free opcost by using Postgres for everything. Arguably if you end up with a monolith of a database, you are paying a higher opcost (imagine if too much caching can affect all CRUD ops in your platform). Or you can manage a cluster of PG instances but that's no less complex---each plugin still comes with its own opcost!
No Silver Bullet, No Free Lunch, and all that. If your problem domain really warrants something outside of relational storage, you're gonna pay that complexity cost one way or another. You can't escape it by shoehorning everything in Postgres, fantastic as a DB as it is.
If you have bunch of files and don't have any structure, yes filesystem is great but the moment when you need consistency & performance (which you need sooner rather than later) use databases.
Investing early doesn't hurt when you build a product that you know will have many writers.
I guess its more the rapid start-up mindset to get it up and running fast to sell the company, and leave the problem for someone else which is why a lot of our world is falling apart...
For example: I worked with Rails from 2009-2024 and I haven't come across a single Rails project in the wild that didn't have the queue du jour installed: sideqik+redis, delayed-job before, etc. And then since it's there, people just end up using.
Like right now I am thinking about a system that has a password reset process and you need to keep track of a user id and a reset token, one or two timestamps, maybe a state variable and a flag or two. That's well under 100 bytes and the cluster size for a typical fs is 4kb or more plus there is the cost of the directory entry. If the OS is Windows it has to ask the Security Manager when ever you open it or delete it which is even more heavyweight.
It's common now for applications that handle lots of little "files" to store them as blobs in SQLlite! See https://sqlite.org/fasterthanfs.html
I have started just using Postgres to back queues. It is simpler (although I have spun up new apps with Redis so many times it is only a small improvement) but more importantly it is cheaper. I really do try a lot of stuff out, so completely removing a infrastructure piece is a nice money saver. Again, not massive but it's cheaper.
The downsides of doing this in the prototype/MVP context are minimal. At the scale of prototype and MVPs, I certainly don't see any difference in performance.
I did note in the graphic it listed Kafka but in the lower table graphic I did not see any Postgres replacement for Kafka. If I am at the scale where I really want Kafka, it is probably for performance and I just can't believe there's anyway Postgres could provide that.
So, I love the flexibility and all-in-one abilities of Postgres for prototyping and making MVPs. But at my job, nobody is proposing exclusively using Postgres for persistence.
SELECT FOR UPDATE SKIP LOCKED works great for turning Postgres into a job queue. It does not work the same way on CRDB and you will likely have to rewrite those queries or use an external job queue.
Unless of course, you already know how to operate rabbitmq.
I've seen a few "Use Postgres for Everything!" posts lately. It seems to be fashionable. It reminds me of the Choose Boring Technology[1] thing from 2018 or so, but more specific to a database.
I think the ideas of "don't add unnecessary dependencies" and "ruthlessly evaluate tradeoffs" and "prefer simplicity" and so on are general and have very little to with postgres, so when I see things like "All you need is X" I roll my eyes a little, because these decisions are highly dependent on your use case, and taken as blanket advice it is generally _bad_ advice even if the underlying rationale is sound.
[1]: https://mcfunley.com/choose-boring-technology
ETA: I am going through their list and so much of this means that you are going to manage your own PG cluster and not take advantage of Aurora or RDS, which means you're already committing to a major tradeoff if you want to use a lot of these custom extensions.
I'm not in the "use Postgres for everything" camp, but only because I think it's too complex to be used like that. It should be replaced with a bunch of simple primitives in this role. No SQL and query planning magic please.
The problem of all the datastores is that are applications (like Wordpress) so you are too late to fix anything deep.
We need "frameworks" (so each sub-component can be used as-is or even swapped) and even wondering what a "system level" data engine could be.
Love FerretDB, but it doesn't really replace MongoDB's GridFS which is main reason why most people who are really using Mongo now day. Anyone knows a good replacement for GridFS?
https://github.com/seanwevans/pg_os
https://github.com/seanwevans/pg_git
https://github.com/seanwevans/pg_gpt2
etc...
I don't believe it's ever easier to manage updating two technologies than one.
Postgres is a good middle ground, though.
First is this Oxide and Friends episode [1] where Bryan and gang explains war stories related to operating Postgres during their Joyent days and why they went with Cockroach DB for Oxide.
Second is this amazing blog from brandur which explains several issues with using Postgres as high throughput queue and some mitigations.
Online forums like Hacker news can be a bit echo chamber-y. It is always good to ensure that the people you are taking advice from are solving the same problem as you.
[1] https://oxide-and-friends.transistor.fm/episodes/whither-coc... [2] https://brandur.org/postgres-queues
https://arango.ai/wp-content/uploads/2025/11/ADB-Community-L...
and it is dead to me. I want my head! I can accept GPL, Apache, MIT or some legit open source license. For my projects I see two possible paths which I want to have open: (1) building a commercial service on top of a database (like my RSS reader) where you can't necessarily draw a clear line between what is allowed and what is not allowed, for instance I have an adaptation layer that makes postgres look like the part of arangodb that I actually use (I do manually rewrite AQL queries into a DSL that extends AlchemyAPI) and if I did something similar over arango is this reselling? (2) an open source project where I want to tell people "go forth and use this code" and not have to hire a lawyer to know what they can and can't do.
Once a vendor has shown they have this attitude, I expect them to change their license for the worse in the future -- I just don't want to invest my time and energy in their platform.
It also has the effect of making software adopting such licenses getting removed from open source distributions.
And if they aren’t calling themselves Open Source, then why do you care?
All the eng. managers I've worked with in the last decade have sworn by Postgres, in the decade before that they were swearing at mongo and getting betrayed by Arangodb switching to a restrictive license and seeing other innovative databases going down the same path means for new side projects I go postgres.