Horton

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

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From: PG Bug reporting form <noreply@postgresql.org>
To: pgsql-bugs@lists.postgresql.org
Cc: eric.cyr@gmail.com
Date: 2018-10-22T14:00:50Z
Lists: pgsql-bugs, pgsql-hackers 
The following bug has been logged on the website:

Bug reference:      15449
Logged by:          Eric Cyr
Email address:      eric.cyr@gmail.com
PostgreSQL version: 10.5
Operating system:   Ubuntu 16.04.2 LTS (Xenial Xerus)
Description:        

CREATE FOREIGN TABLE test_file_fdw_program_limit
    (
      message text
    )
    SERVER pg_log_fdw OPTIONS (program 'echo "test"', format 'csv')
;

--

SELECT * FROM test_file_fdw_program_limit;
/*
OK
*/

SELECT * FROM test_file_fdw_program_limit LIMIT 2;
/*
OK
*/

SELECT * FROM test_file_fdw_program_limit LIMIT 0;
/*
[38000] ERROR: program "echo "test"" failed Detail: child process exited
with exit code 1
*/

--

LIMIT 0 is the easiest way we found to reproduce the error, but we
encountered same issue with LIMIT (< file lines) on a program doing an if
exists + file output stream manipulation.

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.