Documentation about pg_stat_bgwriter

Started by Kyotaro HORIGUCHIover 8 years ago3 messages
#1Kyotaro HORIGUCHI
horiguchi.kyotaro@lab.ntt.co.jp

Hi. While I read the documentation I found the following
description about some columns in pg_stat_bgwriter.

https://www.postgresql.org/docs/devel/static/monitoring-stats.html#pg-stat-bgwriter-view

This table shows cluster-global values, not per-backend values.

maxwritten_clean:
Number of times the background writer stopped a cleaning scan
because it had written too many buffers
buffers_backend:
Number of buffers written directly by a backend
buffers_backend_fsync:
Number of times a backend had to execute its own fsync call
(normally the background writer handles those even when the
backend does its own write)

Since the values are the summary in a cluster, the 'a backend's
in the last two seems wrong *to me*. I suppose the 'a backend'
should be just 'backends' or 'backends other than the background
writer' (This seems a bit verbose.).

regards,

--
Kyotaro Horiguchi
NTT Open Source Software Centerhas

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#2Peter Eisentraut
peter.eisentraut@2ndquadrant.com
In reply to: Kyotaro HORIGUCHI (#1)
Re: Documentation about pg_stat_bgwriter

On 5/10/17 04:38, Kyotaro HORIGUCHI wrote:

Hi. While I read the documentation I found the following
description about some columns in pg_stat_bgwriter.

https://www.postgresql.org/docs/devel/static/monitoring-stats.html#pg-stat-bgwriter-view

This table shows cluster-global values, not per-backend values.

maxwritten_clean:
Number of times the background writer stopped a cleaning scan
because it had written too many buffers
buffers_backend:
Number of buffers written directly by a backend
buffers_backend_fsync:
Number of times a backend had to execute its own fsync call
(normally the background writer handles those even when the
backend does its own write)

Since the values are the summary in a cluster, the 'a backend's
in the last two seems wrong *to me*. I suppose the 'a backend'
should be just 'backends' or 'backends other than the background
writer' (This seems a bit verbose.).

The text looks correct to me as it currently stands. Your alternative
phrasings are also correct. But there is no need to change this, I think.

--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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#3Kyotaro HORIGUCHI
horiguchi.kyotaro@lab.ntt.co.jp
In reply to: Peter Eisentraut (#2)
Re: Documentation about pg_stat_bgwriter

Hello, thank you for the reply.

At Thu, 18 May 2017 20:48:44 -0400, Peter Eisentraut <peter.eisentraut@2ndquadrant.com> wrote in <343d4cdb-e25d-867d-2830-6502eca4df5c@2ndquadrant.com>

On 5/10/17 04:38, Kyotaro HORIGUCHI wrote:

Hi. While I read the documentation I found the following
description about some columns in pg_stat_bgwriter.

https://www.postgresql.org/docs/devel/static/monitoring-stats.html#pg-stat-bgwriter-view

This table shows cluster-global values, not per-backend values.

maxwritten_clean:
Number of times the background writer stopped a cleaning scan
because it had written too many buffers
buffers_backend:
Number of buffers written directly by a backend
buffers_backend_fsync:
Number of times a backend had to execute its own fsync call
(normally the background writer handles those even when the
backend does its own write)

Since the values are the summary in a cluster, the 'a backend's
in the last two seems wrong *to me*. I suppose the 'a backend'
should be just 'backends' or 'backends other than the background
writer' (This seems a bit verbose.).

The text looks correct to me as it currently stands. Your alternative
phrasings are also correct. But there is no need to change this, I think.

It's enough for me to know that it's not a kind of typo. Thanks.

regards,

--
Kyotaro Horiguchi
NTT Open Source Software Center

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