Re: Batching page logging during B-tree build

On Fri, Sep 18, 2020 at 8:39 AM Andrey M. Borodin <x4mmm@yandex-team.ru> wrote:
> Here is PoC with porting that same routine to B-tree. It allows to build B-trees ~10% faster on my machine.

It doesn't seem to make any difference on my machine, which has an
NVME SSD (a Samsung 970 Pro). This is quite a fast SSD, though the
sync time isn't exceptional. My test case is "reindex index
pgbench_accounts_pkey", with pgbench scale 500. I thought that this
would be a sympathetic case, since it's bottlenecked on writing the
index, with relatively little time spent scanning and sorting in
parallel workers.

Can you provide a test case that is sympathetic towards the patch?

BTW, I noticed that the index build is absurdly bottlenecked on
compressing WAL with wal_compression=on. It's almost 3x slower with
compression turned on!

-- 
Peter Geoghegan