Re: remove more archiving overhead

From: Nathan Bossart <nathandbossart(at)gmail(dot)com>
To: David Steele <david(at)pgmasters(dot)net>
Cc: Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, robertmhaas(at)gmail(dot)com, masao(dot)fujii(at)oss(dot)nttdata(dot)com, pgsql-hackers(at)postgresql(dot)org
Subject: Re: remove more archiving overhead
Date: 2022-07-08 16:54:50
Message-ID: 20220708165450.GA2356733@nathanxps13
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On Fri, Jul 08, 2022 at 08:20:09AM -0400, David Steele wrote:
> On 7/7/22 21:56, Kyotaro Horiguchi wrote:
>> Thinking RFC'ish, the meaning of "may" and "must" is significant in
>> this description. On the other hand it uses both "may" and "can" but
>> I thinkthat their difference is not significant or "can" there is
>> somewhat confusing. I think the "can" should be "may" here.
> +1.


>> And since "must" is emphasized, doesn't "may" also needs emphasis?
> I think emphasis only on must is fine.

Yeah, I wanted to emphasize the importance of returning false in this case.
Since it's okay to return true or false in the identical/persisted file
case, I didn't think it deserved emphasis.

> Nathan, I don't see the language about being sure to persist to storage
> here?

It's here:
When an archive library encounters a pre-existing file, it may return
true if the WAL file has identical contents to the pre-existing archive
and the pre-existing archive is fully persisted to storage.

Since you didn't catch it, I wonder if it needs improvement. At the very
least, perhaps we should note that one way to do the latter is to persist
it yourself before returning true, and we could point to basic_archive.c as
an example. However, I'm hesitant to make these docs too much more
complicated than they already are. WDYT?

Nathan Bossart
Amazon Web Services:

Attachment Content-Type Size
v4-0001-Reduce-overhead-of-renaming-archive-status-files.patch text/x-diff 2.2 KB
v4-0002-add-note-about-re-archiving-in-docs.patch text/x-diff 2.6 KB

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