Re: [PATCH 1/4] gitfaq: add advice on monorepos

On 2021-10-20 at 10:54:47, Ævar Arnfjörð Bjarmason wrote:

On Wed, Oct 20 2021, brian m. carlson wrote:

quoted

+[[monorepos]]
+Should we use a monorepo or many individual repos?::
+	This is a decision that is typically made based on an organization's needs and
+	desires for their projects.  Git has several features, such as shallow clone,
+	partial clone, and sparse checkout to make working with large repositories
+	easier, and there is active development on making the monorepo experience
+	better.
++
+However, at a certain size, the performance of a monorepo will likely become
+unacceptable _unless_ you use these features.  If you choose to start with a
+monorepo and continue to grow, you may end up unhappy with the performance
+characteristics at a point where making a change is difficult.  The performance
+of using many smaller repositories will almost always be much better and will
+generally not necessitate the use of these more advanced features.  If you are
+concerned about future performance of your repository and related tools, you may
+wish to avoid a monorepo.
++
+Ultimately, you should make a decision fully informed about the potential
+benefits and downsides, including the capabilities, performance, and future
+requirements for your repository and related tools, including your hosting
+platform, build tools, and other programs you typically use as part of your
+workflow.

In the context of git development we're typically talking about really
big repos when we're talking about monorepos, saying "monorepo"
communicates among other things that the user of that pattern is
unwilling to use splitting up as a way to address any scalability issues
they may have.

But a monorepo doesn't really say anything about size per-se, and it
would be confusing to conflate the two in a FAQ. I may be wrong, perhaps
the term has really come to exclusively refer to colossal size, but I
haven't seen or heard it exclusively (or even mainly) used like that

I routinely hear "monorepo" used to imply repositories of specifically
large size.  However, I'm happy to rephrase to make it clearer.

I bet that the vast majority of monorepo users are never going to
experience scaling problems, e.g. having your laptop dotfiles and
automation of /etc in one repo is a "monorepo", and most companies/teams
that use monorepos I'd bet are in the long tail of size
distribution. They're not going to grow to the size of a MS's, FB's
etc. monorepo, but they might benefit (or not) from the monorepo
/workflow/.

I almost never hear individuals refer to such a configuration as a
monorepo.  Technically, it is one, yes, but I almost always hear it in
the context of an organization's repository covering all of their
services or the entirety of one major project.

I will point out that I personally would run into scaling issues if I
put all of my projects in the same repository.  I have many projects,
and that would quickly become unsustainable, since the resources I have
at my disposal are more limited than most organizations.

Anyway, all of the above can be read as a suggestion that we should
split any discussion of "large repo [that runs into scaling issues]"
from "monorepo", the latter should of course make a passing reference to
scaling (as the pattern will lead to that sooner than not), but IMO not
conflate the two.

I'm happy to clarify, but I think we need to mention the word "monorepo"
specifically because (a) that's the term that's commonly used for this
approach and (b) that approach is one that tends to lead to
significantly greater growth in a single repository leading to scale
problems.
-- 
brian m. carlson (he/him or they/them)
Toronto, Ontario, CA