select limit error in file_fdw

Hello,

I have noticed that since ffa4cbd623, a foreign table that pulls data
from a PROGRAM (in this case an unzip call) will fail if there is a
LIMIT on the SELECT
(while succeeding without LIMIT). Below is an example.
(Table size matters, so larger machines than mine may need more than
those 100000 rows.)

A pre-ffa4cbd623 instance did not have this problem (and neither does
11.1)

This seems like a bug to me.

--------------- 8< ------------------------------
#!/bin/bash

# service=prod
service=dev11 # this is latest dev11 (in 11.1 it still worked;
# commit ffa4cbd623 looks pertinent)

csv_file=/tmp/t.txt

echo "select n from generate_series(1, 100000) as f(n)" | psql -qtAX
service=$service > $csv_file

zip ~/t.zip $csv_file

echo "
drop server if exists test_server cascade;
create server if not exists test_server foreign data wrapper file_fdw;
create schema if not exists tmp;
drop foreign table if exists tmp.t cascade;
create foreign table tmp.t (n int)
server test_server
options (
program 'unzip -p \"/home/aardvark/t.zip\" \"tmp/t.txt\"'
, format 'csv'
, header 'TRUE'
, delimiter E'\t'
);
" | psql -X service=$service

# this works OK:
echo "table tmp.t;" | psql -Xa service=$service | head

# this fails in latest dev11 :
echo "table tmp.t limit 10;" | psql -Xa service=$service
--------------- 8< ------------------------------

Output:

updating: tmp/t.txt (deflated 63%)
DROP SERVER
CREATE SERVER
CREATE SCHEMA
DROP FOREIGN TABLE
CREATE FOREIGN TABLE
table tmp.t;
n
--------
2
3
4
5
6
7
8
table tmp.t limit 10;
ERROR: program "unzip -p "/home/aardvark/t.zip" "tmp/t.txt"" failed
DETAIL: child process exited with exit code 141

it would be nice to get this working again.

Thanks,

Erik Rijkers