Date: Sun, 21 Feb 2021 15:58:59 +0900
From: Michael Paquier <michael@paquier.xyz>
To: Dmitriy Kuzmin <kuzmin.db4@gmail.com>
Cc: pgsql-docs@lists.postgresql.org
Subject: Re: Inaccuracy in wal_receiver_status_interval parameter description
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On Sat, Feb 20, 2021 at 07:49:21PM +1000, Dmitriy Kuzmin wrote:
> I suppose it could be something like this:
> "...Setting this parameter to zero disables status updates on a scheduled
> basis completely. However there are certain conditions when updates are
> still being sent. For example when startup process completes processing WAL
> files or when standby is in synchronous mode and synchronous_commit is set
> to remote_apply. This parameter can only be set in the postgresql.conf file
> or on the server command line."

That's an idea.  While looking at that I found confusing that the
sentence "Setting this parameter to zero disables status updates
completely" was completely separate of the rest, where it sounds like
even forced messages are disabled if the parameter value is zero, but
I think that we should outline that this only applies to the scheduled
replies.  Attached is what I get.  What do you think?
--
Michael

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diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index e81141e45c..752466bb00 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -4503,15 +4503,16 @@ ANY <replaceable class="parameter">num_sync</replaceable> ( <replaceable class="
        view.  The standby will report
        the last write-ahead log location it has written, the last position it
        has flushed to disk, and the last position it has applied.
-       This parameter's
-       value is the maximum amount of time between reports.  Updates are
-       sent each time the write or flush positions change, or at least as
-       often as specified by this parameter.  Thus, the apply position may
-       lag slightly behind the true position.
+       This parameter's value is the maximum amount of time between reports.
+       Updates are sent each time the write or flush positions change, or as
+       often as specified by this parameter if set to a non-zero value.
+       There are additional cases where updates are sent while ignoring this
+       parameter; for example, when processing of the existing WAL completes
+       or when <varname>synchronous_commit</varname> is set to
+       <literal>remove_apply</literal>.
+       Thus, the apply position may lag slightly behind the true position.
        If this value is specified without units, it is taken as seconds.
-       The default value is 10 seconds.
-       Setting this parameter to zero disables status updates completely.
-       This parameter can only be set in
+       The default value is 10 seconds. This parameter can only be set in
        the <filename>postgresql.conf</filename> file or on the server
        command line.
       </para>

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