On 2020/08/24 21:00, Masahiro Ikeda wrote:
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.
Thanks for the patch!
+/* ----------
+ * Backend types
+ * ----------
You seem to forget to add "*/" into the above comment.
This issue could cause the following compiler warning.
../../src/include/pgstat.h:761:1: warning: '/*' within block comment [-Wcomment]
The contents of pg_stat_walwrites are reset when the server
is restarted. Isn't this problematic? IMO since pg_stat_walwrites
is a collected statistics view, basically its contents should be
kept even in the case of server restart.
Regards,
--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION
