Re: Some questions about PostgreSQL’s design.

On Tue, Aug 20, 2024 at 04:46:54PM +0300, Heikki Linnakangas wrote:
> There are pros and cons. With direct I/O, you cannot take advantage of the
> kernel page cache anymore, so it becomes important to tune shared_buffers
> more precisely. That's a downside: the system requires more tuning. For many
> applications, squeezing the last ounce of performance just isn't that
> important. There are also scaling issues with the Postgres buffer cache,
> which might need to be addressed first.
>
> With double write buffering, there are also pros and cons. It also requires
> careful tuning. And replaying WAL that contains full-page images can be much
> faster, because you can write new page images "blindly" without reading the
> old pages first. We have WAL prefetching now, which alleviates that, but
> it's no panacea.

陈宗志, you mimght find this blog post helpful:

https://momjian.us/main/blogs/pgblog/2017.html#June_5_2017

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Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EDB https://enterprisedb.com

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