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

Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> writes:
> Simon Riggs escribi:
>> On 14 November 2012 15:09, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
>>> Here, progname for COPY IN is the user-supplied program that takes filename as
>>> its argument and that writes on standard output.

>> I think we should be using FDWs/SRFs here, not inventing new
>> syntax/architectures for executing external code, so -1 from me.

> Hmm, but then you are forced to write C code, whereas the "external
> program" proposal could have you writing a only shell script instead.

I disagree with Simon's objection also, because neither reading from
nor writing to an external program is likely to fit the model of
reading/updating a table very well. For instance, there's no good
reason to suppose that reading twice will give the same results. So
force-fitting this usage into the FDW model is not going to work well.

Nor do I really see the argument why a "pipe_fdw" module is cleaner
than a "COPY TO/FROM pipe" feature.

regards, tom lane