Description:
------------
pg_copy_from is a wrapper of postgresql syntax COPY test FROM stdin
But in postgresql people usually do this:

COPY test (field1, field2, field3) FROM stdin;

So I can describe fields and its order.

pg_copy_from without fields order is dangerous to use, because table can be changed by somebody.

Test script:
---------------
-- sql:
CREATE TABLE test (
   field1 int,
   field2 int
);


// php:
$rows = [1, 2];
pg_copy_from($db, $table_name, $rows);


-- sql
-- change order of fields
DROP TABLE test;
CREATE TABLE test (
   field2 int,
   field1 int
);


// php script without changes
$rows = [1, 2];
pg_copy_from($db, $table_name, $rows);

//it inserts data into wrong fields

Expected result:
----------------
a new parameter should be added to pg_copy_from to describe fields order 

Actual result:
--------------
result depends of table