| From: | "Bossart, Nathan" <bossartn(at)amazon(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Michael Paquier <michael(at)paquier(dot)xyz>, Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, "pgsql-hackers(at)lists(dot)postgresql(dot)org" <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Use durable_unlink for .ready and .done files for WAL segment removal |
| Date: | 2018-11-27 20:50:05 |
| Message-ID: | 231D39B9-A06A-46E2-84A5-369EF7F70293@amazon.com |
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| Lists: | pgsql-hackers |
On 11/27/18, 2:46 PM, "Andres Freund" <andres(at)anarazel(dot)de> wrote:
> On 2018-11-27 20:43:06 +0000, Bossart, Nathan wrote:
>> I don't have exact figures to share, but yes, a huge number of calls
>> to sync_file_range() and fsync() can use up a lot of time. Presumably
>> Postgres processes files individually instead of using sync() because
>> sync() may return before writing is done. Also, sync() would affect
>> non-Postgres files. However, it looks like Linux actually does wait
>> for writing to complete before returning from sync() [0].
>
> sync() has absolutely no way to report errors. So, we're never going to
> be able to use it. Besides, even postgres' temp files would be a good
> reason to not use it.
Ah, I see. Thanks for clarifying.
Nathan
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