Re: About to add WAL write/fsync statistics to pg_stat_wal view

From: Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com>
To: Masahiro Ikeda <ikedamsh(at)oss(dot)nttdata(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Cc: Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Li Japin <japinli(at)hotmail(dot)com>, kuroda(dot)hayato(at)fujitsu(dot)com, "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com>
Subject: Re: About to add WAL write/fsync statistics to pg_stat_wal view
Date: 2021-02-08 04:01:10
Message-ID: f081d50f-f20d-8706-aba3-f59cddf7a949@oss.nttdata.com
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On 2021/02/05 8:45, Masahiro Ikeda wrote:
> I pgindented the patches.

Thanks for updating the patches!

+ <function>XLogWrite</function>, which nomally called by an
+ <function>issue_xlog_fsync</function>, which nomally called by an

Typo: "nomally" should be "normally"?

+ <function>XLogFlush</function> request(see <xref linkend="wal-configuration"/>)
+ <function>XLogFlush</function> request(see <xref linkend="wal-configuration"/>),

Isn't it better to add a space character just after "request"?

+ INSTR_TIME_SET_CURRENT(duration);
+ INSTR_TIME_SUBTRACT(duration, start);
+ WalStats.m_wal_write_time = INSTR_TIME_GET_MICROSEC(duration);

If several cycles happen in the do-while loop, m_wal_write_time should be
updated with the sum of "duration" in those cycles instead of "duration"
in the last cycle? If yes, "+=" should be used instead of "=" when updating
m_wal_write_time?

+ INSTR_TIME_SET_CURRENT(duration);
+ INSTR_TIME_SUBTRACT(duration, start);
+ WalStats.m_wal_sync_time = INSTR_TIME_GET_MICROSEC(duration);

Also "=" should be "+=" in the above?

Regards,

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

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