Re: WIP patch: add (PRE|POST)PROCESSOR options to COPY

On 11/14/2012 11:56 AM, Tom Lane wrote:
> Andrew Dunstan <andrew@dunslane.net> writes:
>> On 11/14/2012 11:39 AM, Tom Lane wrote:
>>> What happened to the previous proposal of treating the COPY
>>> target as a pipe specification, ie
>> I'd like to be able to filter STDIN if possible - with this syntax how
>> is COPY going to know to hook up STDIN to the program?
> Huh?  That's fairly nonsensical for the backend-side case; there's no
> way that stdin (or stdout) of a backend is going to connect anywhere
> useful for this purpose.  As for doing it on the psql side (\copy),
> I think it would be more or less automatic.  If you do say
>
>     foo | psql -c "\copy tab from 'bar |'" dbname
>
> then bar is going to inherit psql's stdin, which is coming from foo.
>
>             


Why does it make less sense on the backend than COPY foo FROM STDIN ? 
Why shouldn't I want to be able to filter or transform the input? I have 
a client with a pretty complex backend-driven ETL tool. One of the 
annoying things about it is that we have to transfer the file to the 
backend before we can process it. I can imagine this leading to a 
similar annoyance.

cheers

andrew