El 11/04/18 a las 02:04, David Rowley escribió:
> On 11 April 2018 at 09:13, Martín Marqués <martin.marq...@gmail.com> wrote:
>> This is a patch to add some further description, plus the upper and
>> lower limits it has.
>
> Hi,
>
> + for vacuum_cost_delay. The parameter can take a value
> between 1 and 10000.
>
> vacuum_cost_delay should be in <varname> tags.
>
> +1 to mentioning that we sleep for vacuum_cost_delay, but I just don't
> see many other GUCs with mention of their supported range.
Thanks David for having a look.
New version attached with the missing <varname> tags.
> effective_io_concurrency mentions the range it supports, but this
> happens to depend on USE_POSIX_FADVISE, which if undefined the maximum
> setting is 0, which means the docs are wrong in some cases on that.
>
> vacuum_cost_limit seems fairly fixed at 0-10000 with no compile-time
> conditions, so perhaps it's okay, providing we remember and update the
> docs if that ever changes.
I'm also adding a second patch over the config.sgml doc to fix what I
believe is a misguidance in the minimum resolution time modern systems have.
The patch just changes *many* for *some* systems which have a minimum
resolution time of 10 milliseconds.
--
Martín Marqués http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
>From a0563066bb3a0b8e662eb9e28fd5439c4f3dd5df Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mart=C3=ADn=20Marqu=C3=A9s?=
<martin.marq...@2ndquadrant.com>
Date: Fri, 13 Apr 2018 09:39:11 -0300
Subject: [PATCH 1/2] Describe better vacuum_cost_limit, mentioning the lower
and upper values it can take and the fact that once that value is reached the
backend executing vacuum will sleep for vacuum_cost_delay milliseconds.
---
doc/src/sgml/config.sgml | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 5d5f2d23c4..38e4766522 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -1860,8 +1860,9 @@ include_dir 'conf.d'
</term>
<listitem>
<para>
- The accumulated cost that will cause the vacuuming process to sleep.
- The default value is 200.
+ This is the accumulated cost that will cause the vacuuming process to sleep
+ for <varname>vacuum_cost_delay</varname>. The parameter can take a value
+ between 1 and 10000. The default is 200.
</para>
</listitem>
</varlistentry>
--
2.13.6
>From 1b41ff8743b166103fa9d5d303f3e1ffacf36dbf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mart=C3=ADn=20Marqu=C3=A9s?=
<martin.marq...@2ndquadrant.com>
Date: Fri, 13 Apr 2018 09:44:43 -0300
Subject: [PATCH 2/2] In the past there were many systems which which had an
effective resolution time of 10 milliseconds. That's not entirely true any
more, yet there are still *some* systems that still have that minimum
resolution for time.
Suggest changing *many* for *some* to comply with modern times.
---
doc/src/sgml/config.sgml | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 38e4766522..55f64299ad 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -1788,7 +1788,7 @@ include_dir 'conf.d'
when the cost limit has been exceeded.
The default value is zero, which disables the cost-based vacuum
delay feature. Positive values enable cost-based vacuuming.
- Note that on many systems, the effective resolution
+ Note that on some systems, the effective resolution
of sleep delays is 10 milliseconds; setting
<varname>vacuum_cost_delay</varname> to a value that is
not a multiple of 10 might have the same results as setting it
@@ -1941,7 +1941,7 @@ include_dir 'conf.d'
milliseconds, and repeats. When there are no dirty buffers in the
buffer pool, though, it goes into a longer sleep regardless of
<varname>bgwriter_delay</varname>. The default value is 200
- milliseconds (<literal>200ms</literal>). Note that on many systems, the
+ milliseconds (<literal>200ms</literal>). Note that on some systems, the
effective resolution of sleep delays is 10 milliseconds; setting
<varname>bgwriter_delay</varname> to a value that is not a multiple of 10
might have the same results as setting it to the next higher multiple
--
2.13.6
