Re: Possible TODO item: copy to/from pipe

On 5/31/06, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> After re-reading what I just wrote to Andreas about how compression of
> COPY data would be better done outside the backend than inside, it
> struck me that we are missing a feature that's fairly common in Unix
> programs.  Perhaps COPY ought to have the ability to pipe its output
> to a shell command, or read input from a shell command.  Maybe something
> like
>
>         COPY mytable TO '| gzip >/home/tgl/mytable.dump.gz';
>
> (I'm not wedded to the above syntax, it's just an off-the-cuff thought.)
>
> Of course psql would need the same capability, since the server-side
> copy would still be restricted to superusers.
>
> You can accomplish COPY piping now through psql, but it's a bit awkward:
>
>         psql -c "COPY mytable TO stdout" mydb | gzip ...
>
> Thoughts?  Is this worth doing, or is the psql -c approach good enough?

You can accomplish it now with help of FIFOs, like

\! mkfifo /tmp/psqlfifo
\! chmod 666 /tmp/psqlfifo
-- I know 666 is a dangerous number. ;)
\! gzip -9 < /tmp/psqlfifo > /tmp/psqlcopy.gz
COPY foo TO '/tmp/psqlfifo';

...though ability to pipe "directly" is desirable feature.
  Regards,      Dawid