RE: [PoC] Non-volatile WAL buffer

From: Takashi Menjo <takashi(dot)menjo(at)gmail(dot)com>
> I made a new page at PostgreSQL Wiki to gather and summarize information and discussion about PMEM-backed WAL designs and implementations. Some parts of the page are TBD. I will continue to maintain the page. Requests are welcome.
>
> Persistent Memory for WAL
> https://wiki.postgresql.org/wiki/Persistent_Memory_for_WAL

Thank you for putting together the information.

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

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.

* 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)

* What's the situnation like on Windows?

Regards
Takayuki Tsunakawa