Subject: Re: max_wal_size
To: Bruce Momjian <bruce@momjian.us>
Cc: "David G. Johnston" <david.g.johnston@gmail.com>,
 pluzanov@postgrespro.ru, pgsql-docs@lists.postgresql.org
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From: Pavel Luzanov <p.luzanov@postgrespro.ru>
Message-ID: <26906a54-d7cb-2f8e-eed7-e31660024694@postgrespro.ru>
Date: Tue, 2 Jun 2020 23:42:01 +0300
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Hello,

On 02.06.2020 22:35, Bruce Momjian wrote:
> On Thu, May 28, 2020 at 12:21:14PM +0300, p.luzanov@postgrespro.ru wrote:
>> WAL |-----------|-----+-----|-----+-----|-----+----->
>>
>>                     a           b           c
>> CP              +-----+     +-----+     +-----+
>>                  b     e     b     e     b     e
>>
>> Checkpointer process for point A starts at a(b) and ends at a(e).
>> At the end of the work, CP makes a WAL record(plus symbol on WAL line).
>>
>> Back to the max_wal_size description:
>> "Maximum size to let the WAL grow to between automatic WAL checkpoints."
>>
>> As I understand now, this is true when we talk about the checkpoint as a
>> process.
>> "Maximum size to let the WAL grow to between a(b) and b(e), between b(b) and c
>> (e), etc".
> What if we say:
>
> 	"Maximum size to let the WAL grow during automatic WAL checkpoints."
>
> That highlights the "process" part.
>
Really, "during" is associated with the process, while "between" with 
points.

If there is no objection, simpe patch attached.

-----
Pavel Luzanov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company


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diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 4eef970d41..7398806203 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -3085,7 +3085,7 @@ include_dir 'conf.d'
       </term>
       <listitem>
        <para>
-        Maximum size to let the WAL grow to between automatic WAL
+        Maximum size to let the WAL grow during automatic WAL
         checkpoints. This is a soft limit; WAL size can exceed
         <varname>max_wal_size</varname> under special circumstances, such as
         heavy load, a failing <varname>archive_command</varname>, or a high

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