Re: New statistics for tuning WAL buffer size

On 2020/08/21 12:08, tsunakawa(dot)takay(at)fujitsu(dot)com wrote:
> From: Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com>
>> Just idea; it may be worth exposing the number of when new WAL file is
>> created and zero-filled. This initialization may have impact on
>> the performance of write-heavy workload generating lots of WAL. If this
>> number is reported high, to reduce the number of this initialization,
>> we can tune WAL-related parameters so that more "recycled" WAL files
>> can be hold.
>
> Sounds good. Actually, I want to know how much those zeroing affected the transaction response times, but it may be the target of the wait event statistics that Imai-san is addressing.

Maybe, so I'm ok if the first pg_stat_walwriter patch doesn't expose
this number. We can extend it to include that later after we confirm
that number is really useful.

Regards,

--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION