Horton

Re: BUG #15449: file_fdw using program cause exit code error when using LIMIT

Thomas Munro <thomas.munro@enterprisedb.com>

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From: Thomas Munro <thomas.munro@enterprisedb.com>
To: Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>
Cc: Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp>, Tom Lane <tgl@sss.pgh.pa.us>, Eric Cyr <eric.cyr@gmail.com>, PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2018-11-09T07:32:54Z
Lists: pgsql-bugs, pgsql-hackers 
On Fri, Nov 9, 2018 at 6:39 PM Kyotaro HORIGUCHI
<horiguchi.kyotaro@lab.ntt.co.jp> wrote:
> Mmm..I didn't get an error at hand on both CentOS7 and High Sierra.
>
> | $ perl -e 'for (my $i=0; $i< 1000000; $i++) { print "$i\n"; }' | head -5
> ...
> | 4
> | $ echo $?
> | 0

That's the exit code from head.  You can see python or perl's exit
code by adding strace in front (on Linux):

$ strace python -c "for i in range(1000000): print i" | head -5
...
+++ exited with 1 +++

$ strace perl -e 'for (my $i=0; $i< 1000000; $i++) { print "$i\n"; }' | head -5
...
+++ killed by SIGPIPE +++

> create foreign table ft5 (a text) server svf1 options (program 'ruby -e "for i in 1..1000 do puts i; end"');
> select * from ft5 limit 5;
>  a
> ---
>  1
> ...
>  5
> (5 rows)
> (no error)

1000 is not enough... due to buffering, it works.  Try 1000000:

postgres=# create foreign table ft5 (a text) server svf1 options
(program 'ruby -e "for i in 1..1000000 do puts i; end"');
CREATE FOREIGN TABLE
postgres=# select * from ft5 limit 5;
ERROR:  program "ruby -e "for i in 1..1000000 do puts i; end"" failed
DETAIL:  child process exited with exit code 1

-- 
Thomas Munro
http://www.enterprisedb.com

Commits

  1. Handle EPIPE more sanely when we close a pipe reading from a program.

  2. Avoid defining SIGTTIN/SIGTTOU on Windows.

  3. Leave SIGTTIN/SIGTTOU signal handling alone in postmaster child processes.

  4. Remove some unnecessary pqsignal() calls to shave a few cycles off

  5. Fix handling of SIGCHLD, per recent pghackers discussion: on some

  6. The new files for statistical system views.

  7. Remove fork()/exec() and only do fork(). Small cleanups.