Re: New statistics for tuning WAL buffer size

On 2020-09-28 12:43, Amit Kapila wrote:
> On Mon, Sep 28, 2020 at 8:24 AM Kyotaro Horiguchi
> <horikyota(dot)ntt(at)gmail(dot)com> wrote:
>>
>> At Mon, 28 Sep 2020 08:11:23 +0530, Amit Kapila
>> <amit(dot)kapila16(at)gmail(dot)com> wrote in
>> > One other thing that occurred to me today is can't we keep this as
>> > part of PgStat_GlobalStats? We can use pg_stat_reset_shared('wal'); to
>> > reset it. It seems to me this is a cluster-wide stats and somewhat
>> > similar to some of the other stats we maintain there.
>>
>> I like that direction, but PgStat_GlobalStats is actually
>> PgStat_BgWriterStats and cleard by a RESET_BGWRITER message.
>>
>
> Yeah, I think if we want to pursue this direction then we probably
> need to have a separate message to set/reset WAL-related stuff. I
> guess we probably need to have a separate reset timestamp for WAL. I
> think the difference would be that we can have one structure to refer
> to global_stats instead of referring to multiple structures and we
> don't need to issue separate read/write calls but OTOH I don't see
> many disadvantages of the current approach as well.

IIUC, if we keep wal stats as part of PgStat_GlobalStats,
don't we need to add PgStat_ArchiverStats and PgStat_SLRUStats
to PgStat_GlobalStats too?

Since this is refactoring, I think it's better to make another patch
after the current patch is merged.

Regards,
--
Masahiro Ikeda
NTT DATA CORPORATION