On 2023-02-11 13:36:51 -0800, Andres Freund wrote:
> Even though it's not a correctness issue, it seems to me that
> DropRelationsAllBuffers() etc ought to check if the buffer is BM_TAG_VALID,
> before doing anything further. Particularly in DropRelationsAllBuffers(), the
> check we do for each buffer isn't cheap. Doing it for buffers that don't even
> have a tag seems .. not smart.
There's a small regression for a single relation, but after that it's a clear
benefit.
32GB shared buffers, empty. The test creates N new relations and then rolls
back.
tps tps
num relations HEAD precheck
1 46.11 45.22
2 43.24 44.87
4 35.14 44.20
8 28.72 42.79
I don't understand the regression at 1, TBH. I think it must be a random code
layout issue, because the same pre-check in DropRelationBuffers() (exercised
via TRUNCATE of a newly created relation), shows a tiny speedup.
