Re: ci: CCache churns through available space too quickly

On Fri Jun 5, 2026 at 8:09 PM UTC, Andres Freund wrote:
> Hi,
>
> I noticed that a handfull of CI runs already lead to exceeding the available
> cache space. One can pay for more cache space, but I think the problem is
> more that what we currently do doesn't work well.
>
> With cirrus-ci all branches shared one cache, but that's not the case with
> github actions. Except for being able to read caches from the default branch
> (master in our case), other branches have completely separate cache
> namespaces. That's probably the right call, safety wise, but makes our ccache
> approach .. not great.
>
> We should only upload a new cache when the ccache cache hit ratio of the
> existing cache entry has gotten low.

I had started reviewing this patch the day it was originally sent, but
due to circumstances I couldn't finish the review before it was
committed. I had some thoughts with regard to improving the Python
script itself. Attached are some improvements that make the code
a little more pythonic as well as more easily usable locally for testing
purposes. Some of the patches may be more valuable than others.

--
Tristan Partin
PostgreSQL Contributors Team
AWS (https://aws.amazon.com)