Re: Batching page logging during B-tree build

> 23 сент. 2020 г., в 23:29, Andres Freund <andres(at)anarazel(dot)de> написал(а):
>
> Hi,
>
> On 2020-09-23 11:19:18 -0700, Peter Geoghegan wrote:
>> On Fri, Sep 18, 2020 at 8:39 AM Andrey M. Borodin <x4mmm(at)yandex-team(dot)ru> wrote:
>>> Here is PoC with porting that same routine to B-tree. It allows to build B-trees ~10% faster on my machine.
>
> I wonder what the effect of logging WAL records as huge as this (~256kb)
> is on concurrent sessions. I think it's possible that logging 32 pages
> at once would cause latency increases for concurrent OLTP-ish
> writes. And that a smaller batch size would reduce that, while still
> providing most of the speedup.

Indeed, on my machine performance is indistinguishable between batches of 8, 16 and 32 pages, while still observable (~3...8%) with 8 against 4.

Best regards, Andrey Borodin,