Re: [patch] [doc] Clarify that signal functions have no feedback

On 02/11/2020 18:02, David G. Johnston wrote:
> diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
> index bf6004f321..43bc2cf086 100644
> --- a/doc/src/sgml/func.sgml
> +++ b/doc/src/sgml/func.sgml
> @@ -23892,7 +23892,8 @@ SELECT collation for ('foo' COLLATE "de_DE");
>
> <para>
> The functions shown in <xref
> - linkend="functions-admin-signal-table"/> send control signals to
> + linkend="functions-admin-signal-table"/> send uni-directional
> + control signals to
> other server processes. Use of these functions is restricted to
> superusers by default but access may be granted to others using
> <command>GRANT</command>, with noted exceptions.

The "uni-directional" sounds a bit redundant, "send" implies that it's
uni-directional I think.

> @@ -23900,7 +23901,8 @@ SELECT collation for ('foo' COLLATE "de_DE");
>
> <para>
> Each of these functions returns <literal>true</literal> if
> - successful and <literal>false</literal> otherwise.
> + the signal was successfully sent and <literal>false</literal>
> + if the sending of the signal failed.
> </para>

This is a good clarification.

> <table id="functions-admin-signal-table">
> @@ -23948,7 +23950,11 @@ SELECT collation for ('foo' COLLATE "de_DE");
> server to reload their configuration files. (This is initiated by
> sending a <systemitem>SIGHUP</systemitem> signal to the postmaster
> process, which in turn sends <systemitem>SIGHUP</systemitem> to each
> - of its children.)
> + of its children.) Inspection of the relevant
> + <link linkend="view-pg-file-settings">pg_file_settings</link>
> + or
> + <link linkend="view-pg-hba-file-rules">pg_hba_file_rules</link> views
> + is recommended after making changes but before signaling the server.
> </para></entry>
> </row>

I don't understand this recommendation. What is the user supposed to
look for in those views? And why before signaling the server?

[me reads what those views do]. Oh, I see, the idea is that you can use
those views to check the configuration for errors, before applying the
changes. How about this:

You can use the <link
linkend="view-pg-file-settings">pg_file_settings</link> and <link
linkend="view-pg-hba-file-rules">pg_hba_file_rules</link> views to check
the configuration files for possible errors, before reloading.

- Heikki