Re: archive modules

On Fri, Oct 14, 2022 at 12:10:18PM +0530, Bharath Rupireddy wrote:
> +        ereport(ERROR,
> +                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
> +                 errmsg("both archive_command and archive_library specified"),
> +                 errdetail("Only one of archive_command,
> archive_library may be set.")));
> 
> The above errmsg looks informational. Can we just say something like
> below?  It doesn't require errdetail as the errmsg says it all. See
> the other instances elsewhere [2].
> 
>         ereport(ERROR,
>                 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
>                  errmsg("cannot specify both \"archive_command\" and
> \"archive_library\"")));

I modeled this after the ERROR that error_multiple_recovery_targets()
emits.  I don't think there's really any material difference between your
proposal and mine, but I don't have a strong opinion.

> 2) I think we have a problem - set archive_mode and archive_library
> and start the server, then set archive_command, reload the conf, see
> [3] - the archiver needs to error out right? The archiver gets
> restarted whenever archive_library changes but not when
> archive_command changes. I think the right place for the error is
> after or at the end of HandlePgArchInterrupts().

Good catch.  You are right, this is broken.  I believe that we need to
check for the misconfiguration in HandlePgArchInterrupts() in addition to
LoadArchiveLibrary().  I will work on fixing this.

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com