[irrational]

Can you go into more about what these problems are? I've always used databases (about 15 years on Oracle and about 5 years on Postgres) and I'm not sure if I know what problems you are referring to. Maybe I have experienced them, but have thought of them by a different name.

SQL - I'm not sure what the problems are with SQL. But it is like a second language to me so maybe I experienced these problems long ago and have forgotten about them.

ORM - I never use an ORM, so I have no idea what the problems might be.

testing latency - I don't know what this refers to.

dependency - ditto

[bradfitz]

SQL is fine. We use it for some things. But not writing SQL is easier than writing SQL. Our data is small enough to fit in memory. Having all the data in memory and just accessible is easier than doing SQL + network round trips to get anything.

ORMs: consider yourself lucky. They try to make SQL easy by auto-generating terrible SQL.

Testing latency: we want to run many unit tests very quickly without high start-up cost. Launching MySQL/PostgreSQL docker containers and running tests against Real Databases is slower than we'd like.

Dependencies: Docker and those MySQL or PostgreSQL servers in containers.

[nmjohn]

Can you put some numbers on how much time is too much? I've never seen anyone go this far to avoid using a database for what sounds like the only "real" reason is to avoid testing latency (a problem which has many other solutions) so I am really confused, but curious to understand!

[bradfitz]

Running all of our control server tests (including integration tests) right now takes 8 seconds, and we're not even incredibly happy with that. There's no reason it should even be half that.

So it's not really in our patience budget for adding a mysqld or postgres start up (possible docker pull, create its schema, etc).

[ac2u]

>right now takes 8 seconds, and we're not even incredibly happy with that

With the amount of explaining and skepticism you're having to deal with in most of the threads here (plenty of reasonable questions, some seem to approach the question with the assumption that your approach is totally wrong) I feel compelled to comment on how nice such a fast feedback loop would be just so it's known that you're not listing these benefits into an ether that doesn't appreciate them.

[disgruntledphd2]

Yeah, I'm inspired to reduce the cost of my tests to get to a better place as a result of this.

Mind you, I build ML/statisical models, so my integration/e2e tests are definitely not going to get down to 8 seconds.

[xupybd]

Wow that's really quick. I can see why that would be very desirable.

It would create a nice flow to get feedback from your test suite that quickly.

[viraptor]

Not sure what their requirements are, but I'm using a "spin up an isolated postgres instance per test run" solution and end up with ~3s overhead to do that. (Using https://pypi.org/project/testing.postgresql/

Edit: 3s for global setup/teardown. Not per test function/suite.

[irrational]

Ah, we don't use Docker or any other container technology. Maybe that is why we aren't seeing the latency issues you are referring to.

[bradfitz]

Docker itself doesn't add much latency. It just makes getting MySQL and PostgreSQL easier. If anything, it helps with dependencies. The database server startup still isn't great, though.

[nicoburns]

If you don't use Docker, you can just leave the database server running in the background, which removes the startup latency (you can of course do this with Docker too, but Docker has a tendency to use quite a few resources when left running in the background, which a database server on it's own won't).

[bradfitz]

So then every engineer needs to install & maintain a database on their machines. (Hope they install the right version!)

I mean, that's what my old company did pre-Docker. It works, but it's tedious.

[irrational]

Do the developers not have an internet connection? Why can’t they just hit a database running in the cloud or your own server somewhere?

[throwdbaaway]

There is a middle path -- use lxd. This way, the mysqld/postgres process can always be running, while the dev machine remains clean.

(But of course the battery will drain a little faster if it is a laptop)

[nicoburns]

I mean that's an `apt install postgres` or `brew install postgres` away. Takes about 5 minutes. I guess it could become a pain if you need to work with multiple different versions at once.

[cpuguy83]

Would love to know what resources you are speaking of here.

We've definitely done some whack-a-mole with allocations in the engine, and of course there's always things getting changed/added still.

[majormajor]

Were you doing a lot of logic in SQL itself? Sounds like not really, but then I'm surprised you'd have so many tests hitting the DB directly, vs most feature logic living above that layer in a way that doesn't need the DB running at all.

[jolux]

Why are your unit tests touching a database? I’m a real stickler about keeping unit tests isolated, because once I/O gets involved, they invariably become much less reliable and as you mention, too slow.

[bradfitz]

Sorry, I should've just said tests. Our tests overall are a mix of unit tests and integration tests and all sizes in between, depending on what they want to test.

[jolux]

I see. That makes more sense.

[jgraettinger1]

I think the "database" label is tripping up the conversation here. What's being talked about here, really, is fast & HA coordination over a (relatively) small amount of shared state by multiple actors within a distributed system. This is literally Etcd's raison d'etre, it excels at this use case.

There are many operational differences between Etcd and a traditional RDBMs, but the biggest ones are that broadcasting updates (so that actors may react) is a core operation, and the MVCC log is "exposed" (via ModRevision) so that actors can resolve state disagreements (am I out of date, or are you?).