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");
>  
>     
>      The functions shown in  -    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
>      GRANT, 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");
>  
>     
>      Each of these functions returns true if
> -    successful and false otherwise.
> +    the signal was successfully sent and false
> +    if the sending of the signal failed.
>     

This is a good clarification.

>     
> @@ -23948,7 +23950,11 @@ SELECT collation for ('foo' COLLATE "de_DE");
>          server to reload their configuration files.  (This is initiated by
>          sending a SIGHUP signal to the postmaster
>          process, which in turn sends SIGHUP to each
> -        of its children.)
> +        of its children.)  Inspection of the relevant
> +        pg_file_settings
> +        or
> +        pg_hba_file_rules views
> +        is recommended after making changes but before signaling the server.
>         
>        

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 pg_file_settings and pg_hba_file_rules views to check 
the configuration files for possible errors, before reloading.

- Heikki