Re: [PoC] Non-volatile WAL buffer

Hi Takayuki,

Thank you for your helpful comments.

In "Allocates WAL buffers on shared buffers", "shared buffers" should be
> DRAM because shared buffers in Postgres means the buffer cache for database
> data.
>

That's true. Fixed.

> I haven't tracked the whole thread, but could you collect information like
> the following? I think such (partly basic) information will be helpful to
> decide whether it's worth casting more efforts into complex code, or it's
> enough to place WAL on DAX-aware filesystems and tune the filesystem.
>
> * What approaches other DBMSs take, and their performance gains (Oracle,
> SQL Server, HANA, Cassandra, etc.)
> The same DBMS should take different approaches depending on the file type:
> Oracle recommends different things to data files and REDO logs.
>

I also think it will be helpful. Adding "Other DBMSes using PMEM" section.

* The storage capabilities of PMEM compared to the fast(est) alternatives
> such as NVMe SSD (read/write IOPS, latency, throughput, concurrency, which
> may be posted on websites like Tom's Hardware or SNIA)
>

This will be helpful, too. Adding "Basic performance" subsection under
"Overview of persistent memory (PMEM)."

* What's the situnation like on Windows?
>

Sorry but I don't know Windows' PMEM support very much. All I know is that
Windows Server 2016 and 2019 supports PMEM (2016 partially) [1] and PMDK
supports Windows [2].

All the above contents will be updated gradually. Please stay tuned.

Regards,

[1]
https://docs.microsoft.com/en-us/windows-server/storage/storage-spaces/deploy-pmem
[2]
https://docs.pmem.io/persistent-memory/getting-started-guide/installing-pmdk/installing-pmdk-on-windows

--
Takashi Menjo <takashi(dot)menjo(at)gmail(dot)com>