Re: New statistics for tuning WAL buffer size

On 2020-08-24 20:45, Masahiro Ikeda wrote:
> Hi, thanks for useful comments.
> 
>>> I agree to expose the number of WAL write caused by full of WAL 
>>> buffers.
>>> It's helpful when tuning wal_buffers size. Haribabu separated that 
>>> number
>>> into two fields in his patch; one is the number of WAL write by 
>>> backend,
>>> and another is by background processes and workers. But I'm not sure
>>> how useful such separation is. I'm ok with just one field for that 
>>> number.
>> I agree with you.  I don't think we need to separate the numbers for 
>> foreground processes and background ones.  WAL buffer is a single 
>> resource.  So "Writes due to full WAL buffer are happening.  We may be 
>> able to boost performance by increasing wal_buffers" would be enough.
> 
> I made a patch to expose the number of WAL write caused by full of WAL 
> buffers.
> I'm going to submit this patch to commitfests.
> 
> As Fujii-san and Tsunakawa-san said, it expose the total number
> since I agreed that we don't need to separate the numbers for
> foreground processes and background ones.
> 
> By the way, do we need to add another metrics related to WAL?
> For example, is the total number of WAL writes to the buffers useful
> to calculate the dirty WAL write ratio?
> 
> Is it enough as a first step?

I forgot to rebase the current master.
I've attached the rebased patch.

Regards,
-- 
Masahiro Ikeda
NTT DATA CORPORATION