Message-ID: <983e1c05-d479-dec3-b96e-0e5e359f5aa7@pgmasters.net>
Date: Fri, 8 Jul 2022 13:02:51 -0400
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0)
 Gecko/20100101 Thunderbird/91.11.0
Subject: Re: remove more archiving overhead
Content-Language: en-US
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: Kyotaro Horiguchi <horikyota.ntt@gmail.com>, robertmhaas@gmail.com,
 masao.fujii@oss.nttdata.com, pgsql-hackers@postgresql.org
References: <20220707182251.GA2255242@nathanxps13>
 <ba7e11b0-054d-1d26-bafd-7a2bc97f11f7@pgmasters.net>
 <20220707220716.GA2258527@nathanxps13>
 <20220708.105652.1551158050191356887.horikyota.ntt@gmail.com>
 <44dbf5e4-8eec-da56-daba-755128b3723e@pgmasters.net>
 <20220708165450.GA2356733@nathanxps13>
From: David Steele <david@pgmasters.net>
In-Reply-To: <20220708165450.GA2356733@nathanxps13>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Archived-At: 
 <https://www.postgresql.org/message-id/983e1c05-d479-dec3-b96e-0e5e359f5aa7%40pgmasters.net>
Precedence: bulk

On 7/8/22 12:54, Nathan Bossart wrote:
> On Fri, Jul 08, 2022 at 08:20:09AM -0400, David Steele wrote:
> 
>> 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?

I think I wrote this before I'd had enough coffee. "fully persisted to 
storage" can mean many things depending on the storage (Posix, CIFS, S3, 
etc.) so I think this is fine. The basic_archive module is there for 
people who would like implementation details for Posix.

Regards,
-David