> > The probably useful next step would be to pass the current length to
the
> > archive_command,
> > so it can write the filled part of the file without the need for a
> > filter.
>
> I can see that helping a lot, but not by writing onto the file on
disk.
> If the file is nearly empty, that would be a lot of disk I/O which
doesn't
> need to happen.
I think you misunderstood what I meant.
The actual archive command is constructed by expanding certain
placeholders.
I am suggesting to add such a placeholder for the size of the filled
part of the log.
A hypothetical example (note suggested %b placeholder for size in
bytes):
archive_command=dd if=%p of=/backup/WAL/%f bs=1 count=%b
This allows to avoid unnecessary io for the backup of partially filled
logs.
Andreas