Re: Two fsync related performance issues?
| От | Paul Guo |
|---|---|
| Тема | Re: Two fsync related performance issues? |
| Дата | |
| Msg-id | CAEET0ZERL+UGw9aG6zh=yF7tcnVB5g1UbFE8+v9DvVwhwTgo9w@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Two fsync related performance issues? (Michael Paquier <michael@paquier.xyz>) |
| Ответы |
Re: Two fsync related performance issues?
|
| Список | pgsql-hackers |
Thanks for the replies.
On Tue, May 12, 2020 at 2:04 PM Michael Paquier <michael@paquier.xyz> wrote:
On Tue, May 12, 2020 at 12:55:37PM +0900, Fujii Masao wrote:
> On 2020/05/12 9:42, Paul Guo wrote:
>> 1. StartupXLOG() does fsync on the whole data directory early in
>> the crash recovery. I'm wondering if we could skip some
>> directories (at least the pg_log/, table directories) since wal,
>> etc could ensure consistency.
>
> I agree that we can skip log directory but I'm not sure if skipping
> table directory is really safe. Also ISTM that we can skip the directories
> that those contents are removed or zeroed during recovery,
> for example, pg_snapshots, pg_substrans, etc.
Basically excludeDirContents[] as of basebackup.c.
table directories & wal fsync probably dominates the fsync time. Do we
know any possible real scenario that requires table directory fsync?
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