> On 18 Dec 2023, at 22:30, Robert Haas <robertmh...@gmail.com> wrote:
>
> On Mon, Dec 18, 2023 at 12:04 PM Robert Haas <robertmh...@gmail.com> wrote:
>> certain sense they are competing for the same job. However, they do
>> aim to alleviate different TYPES of contention: the group XID update
>> stuff should be most valuable when lots of processes are trying to
>> update the same page, and the banks should be most valuable when there
>> is simultaneous access to a bunch of different pages. So I'm not
>> convinced that this patch is a reason to remove the group XID update
>> mechanism, but someone might argue otherwise.
>
> Hmm, but, on the other hand:
>
> Currently all readers and writers are competing for the same LWLock.
> But with this change, the readers will (mostly) no longer be competing
> with the writers. So, in theory, that might reduce lock contention
> enough to make the group update mechanism pointless.
One page still accommodates 32K transaction statuses under one lock. It feels
like a lot. About 1 second of transactions on a typical installation.
When the group commit was committed did we have a benchmark to estimate
efficiency of this technology? Can we repeat that test again?
Best regards, Andrey Borodin.
