Re: Monitoring time of fsyncing WALs

On Wed, Jun 27, 2018 at 10:27 PM, Michael Paquier <michael@paquier.xyz> wrote:
> On Wed, Jun 27, 2018 at 07:32:18PM +0300, Konstantin Knizhnik wrote:
>> I wonder why we are monitoring time of writing to WAL, but not time of
>> fsyncing WAL segments?
>> Is there are principle reason for it or just because nobody added it yet?
>> If so, please find very small patch which adding WAIT_EVENT_WAL_FSYNC event
>> type.
>
> Let's name it WAIT_EVENT_WAL_SYNC as it is more consistent with the
> other wait events of the same type, and also list the wait event
> alphabetically everywhere this is added.  I have also reworded the
> documentation to be more consistent.
>
>> Our engineers in PgPro complain me that there is no information about time
>> spent in syncing WALs...
>> Unfortunately Postgres still is not able to aggregate this statistic. But at
>> least we have pg_wait_sampling extension for it:
>> https://github.com/postgrespro/pg_wait_sampling
>
> Complain justified.  It is a bit too late for v11 I think though, so
> let's wait for v12 to open for business, and then I'll apply the patch
> at if there are no objections until then.

Are there other instances of fsync() that also need to be covered?

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
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