How many scenarios are there where the rename both matters (beyond taste and philosophy) and is across interface boundaries?

Surely if it is an advantage to rename once in a ginormous, single code base there must also be leaky abstractions, poorly defined interfaces, god objects, etc present at the same time?

Whenever I find I need to rename anything across domains, it's a matter of updating the "core" repository and then just pulling the newest version.

Monorepo is not necessarily synced deployment, and even if it was, each deployment of a single component is usually racy with itself (as long as you're deploying to at least two nodes).

Which means that you've got to do independent backwards-compatible changes anyway, and that for anything remotely complex, you are better off with separate branches (and PR/MRs) anyway.

Monorepos mostly have a benefit for trivial changes across all repos (eg. we've decided to rename our "Shop" to "Shoppe"), where it doesn't really take much to explain with multiple repos, but is mostly a lot of tedious work to get all the PRs up and such.

I think that when you have large enough systems that works. I do not believe that "microservice" is the right size for repo splits.

Sometimes you have to ship a feature. Shipping that requires changing 3 parts of your app. A lot of times that _entire_ set of changes is less than 100 lines of code.

Having a full vision of what is being accomplished across your system in one go is very helpful for reviewing code! It justifies the need for changes, makes it easier to propose alternatives, and makes the go/no-go operation much more straightforward.

At a smaller scale, you often see the idea of splitting frontend and backend into separate repos. Of course you can ship an API and then ship the changes to the frontend. But for a lot of trivial stuff, just having both lets you actually see API usage in practice.

I think this is much more applicable for companies under 100 people though. When you get super large you're going to put into place a superstructure that will cause these splits anyways.

TBH, I am not a fan of frontend/backend split either: ideally, you'd still be splitting per component/service, so frontend and backend for a single thing could live in the same place: you get the benefit of seeing the API in use with each PR, without the costs of monorepo otherwise.

Most projects start out as monoliths (which is good) and splitting up on this axis is unfortunately very hard/costly.

This is why I'm a fan of tools like Bazel, where you can still get most of the tooling benefits from a single repo, but get testing speed benefits (and, if you roll that way, the design benefits from the separation) of a multirepo setup.

Unfortunately it's hard for me to recommend Bazel, it's such an uphill climb to get things working within that system.

What I took away from TFA is that monorepo management at this scale is “extremely frustrating” too.

ISTM that the complexity of managing any repo will be bounded by the size of that repo; a monorepo, being unbounded in size, will, in time, become arbitrarily complex to manage.

While a multirepo might occasionally require developers to apply changes to more than one repo at a time, I’ve never found this to be much more than a minor inconvenience; one that could be solved readily with simple tooling, if we had ever felt that the “problem” was even worth solving.

At my $dailyjob we (kinda unfortunately) went with tons of repositories and libraries upon libraries, and the only sane way for me to make changes across multiple repos is combining them into single build locally. In .NET it's not that complex - remove a Nuget dependency from your project, and add reference to locally checked-out repository and make sure you're using proper tags. It's mundane, happens to be frustrating, but I can make it work.

The process you're describing looks like some trial and error PRs...

Multirepo also allows you to roll out that change incrementally instead of big banging all the time.

Well for trivial changes it's even worse, cuz instead of "change 3 files across this boundary" it's "send 2 sets of changes to different places, babysit it until merging, then send a third PR in the integration point to use the updated vesrion and then get it merged".

Meanwhile reviewers don't have context about changes, so it's easier to get lost in the weeds.

It's not always this, of course. But I think that way too many tools are based on "repo" being the largest element, so things like cross-repo review are just miserable.

But in the monorepo you almost never can do the change in a single commit as it will cause incompatibilities during gradual deployment

Canva engineer here: we do compatibility checking of interservice contracts (Proto) to ensure that gradual deploys are always safe and can always be safely rolled back.

Google does such a thing in its monorepo quite routinely.