Re: Add Information during standby recovery conflicts

On 2020-Dec-01, Fujii Masao wrote:

> +            if (proc)
> +            {
> +                if (nprocs == 0)
> +                    appendStringInfo(&buf, "%d", proc->pid);
> +                else
> +                    appendStringInfo(&buf, ", %d", proc->pid);
> +
> +                nprocs++;
> 
> What happens if all the backends in wait_list have gone? In other words,
> how should we handle the case where nprocs == 0 (i.e., nprocs has not been
> incrmented at all)? This would very rarely happen, but can happen.
> In this case, since buf.data is empty, at least there seems no need to log
> the list of conflicting processes in detail message.

Yes, I noticed this too; this can be simplified by changing the
condition in the ereport() call to be "nprocs > 0" (rather than
wait_list being null), otherwise not print the errdetail.  (You could
test buf.data or buf.len instead, but that seems uglier to me.)