RE: [PoC] Non-volatile WAL buffer

Hello Amit,

> I apologize for not having any opinion on the patches themselves, but let me point out that it's better to base these
> patches on HEAD (master branch) than REL_12_0, because all new code is committed to the master branch,
> whereas stable branches such as REL_12_0 only receive bug fixes. Do you have any specific reason to be working
> on REL_12_0?

Yes, because I think it's human-friendly to reproduce and discuss performance measurement. Of course I know all new accepted patches are merged into master's HEAD, not stable branches and not even release tags, so I'm aware of rebasing my patchset onto master sooner or later. However, if someone, including me, says that s/he applies my patchset to "master" and measures its performance, we have to pay attention to which commit the "master" really points to. Although we have sha1 hashes to specify which commit, we should check whether the specific commit on master has patches affecting performance or not because master's HEAD gets new patches day by day. On the other hand, a release tag clearly points the commit all we probably know. Also we can check more easily the features and improvements by using release notes and user manuals.

Best regards,
Takashi

--
Takashi Menjo <takashi(dot)menjou(dot)vg(at)hco(dot)ntt(dot)co(dot)jp>
NTT Software Innovation Center
> -----Original Message-----
> From: Amit Langote <amitlangote09(at)gmail(dot)com>
> Sent: Monday, February 17, 2020 1:39 PM
> To: Takashi Menjo <takashi(dot)menjou(dot)vg(at)hco(dot)ntt(dot)co(dot)jp>
> Cc: Robert Haas <robertmhaas(at)gmail(dot)com>; Heikki Linnakangas <hlinnaka(at)iki(dot)fi>; PostgreSQL-development
> <pgsql-hackers(at)postgresql(dot)org>
> Subject: Re: [PoC] Non-volatile WAL buffer
>
> Menjo-san,
>
> On Mon, Feb 17, 2020 at 1:13 PM Takashi Menjo <takashi(dot)menjou(dot)vg(at)hco(dot)ntt(dot)co(dot)jp> wrote:
> > I applied my patchset that mmap()-s WAL segments as WAL buffers to refs/tags/REL_12_0, and measured and
> analyzed its performance with pgbench. Roughly speaking, When I used *SSD and ext4* to store WAL, it was
> "obviously worse" than the original REL_12_0.
>
> I apologize for not having any opinion on the patches themselves, but let me point out that it's better to base these
> patches on HEAD (master branch) than REL_12_0, because all new code is committed to the master branch,
> whereas stable branches such as REL_12_0 only receive bug fixes. Do you have any specific reason to be working
> on REL_12_0?
>
> Thanks,
> Amit