Bryan Boreham

You want a new label which contains all the values of a label that disapeared under aggregation? Interesting idea, though I don't think `label_join` is the right name for that.

It wouldn't be a function, in the sense that functions work currently. It could be added as an optional part of `sum`, maybe `sum by(instance) concat_as(datacenters) (...)`. Maybe some cryptic...

CI is failing on Windows with an error I can't believe is connected to this change: ``` testing.go:1097: TempDir RemoveAll cleanup: remove C:\Users\RUNNER~1\AppData\Local\Temp\TestReadCheckpointcompress=false1728930424\001\wal\00000030: The process cannot access the file because...

I fixed the lint error.

I see very close correspondance between the 'main' and 'PR' lines on the dashboard, which matches what the benchmarks say. You can cancel the prombench. (I assume I cannot, as...

I pushed an update which removes `Reserve()` and `Append()`, instead adding a `SimpleBuilder` which is like `labels.Builder` but streamlined for the case where we only add unique labels.

Sure; note #10991 is the interesting one; this is just laying the groundwork.

> I wonder if we could merge this and then feature flag this change I assume you mean merge #10887 and feature-flag #10991? That is an interesting idea, however the...

> Oh, I was thinking we could turn labels into an interface While conceptually that is a fine idea; in practice we now need 16 bytes for the interface pointer...

There have been a few fixes in #10991 which also affect this branch; I should move them here, and particularly the extra tests. I think this change will be disruptive...