From: Tom Lane <tgl@sss.pgh.pa.us>
To: Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp>
cc: Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>,
        thomas.munro@enterprisedb.com, eric.cyr@gmail.com,
        pgsql-hackers@lists.postgresql.org
Subject: Re: BUG #15449: file_fdw using program cause exit code error when
 using LIMIT
In-reply-to: <5BEA9E82.1080709@lab.ntt.co.jp>
References: <5BE4318F.4040002@lab.ntt.co.jp>
 <20181109.143931.243136889.horiguchi.kyotaro@lab.ntt.co.jp>
 <5BE552ED.4040304@lab.ntt.co.jp>
 <20181112.185214.76711162.horiguchi.kyotaro@lab.ntt.co.jp>
 <5BE966F4.1040702@lab.ntt.co.jp> <5BEA9E82.1080709@lab.ntt.co.jp>
Comments: In-reply-to Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp>
	message dated "Tue, 13 Nov 2018 18:50:58 +0900"
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Date: Fri, 16 Nov 2018 12:20:51 -0500
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Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp> writes:
> * I think it's better to ignore the SIGPIPE failure in 
> ClosePipeToProgram if we were in a COPY FROM PROGRAM that was allowed to 
> terminate early and keep the behavior as-is otherwise.  If we ignore 
> that failure unconditionally in that function, eg, COPY TO PROGRAM would 
> fail to get a (better) error message in CopySendEndOfRow or EndCopy when 
> the invoked program was terminated on SIGPIPE, as discussed before [1]. 
>   And to do so, I added a new argument to BeginCopyFrom to specify 
> whether COPY FROM PROGRAM can terminate early or not.

If we do that, it makes this not back-patchable, I fear --- the fact
that file_fdw is calling BeginCopyFrom seems like sufficient evidence
that there might be third-party callers who would object to an API
break in minor releases.  That seems unfortunate for a bug fix.

Are we sufficiently convinced that we must have the dont-allow-partial
option to not fix this in the back branches?  I'm not.

			regards, tom lane