Just an idea. Or a study or a sketch. As you like:

#!/usr/bin/env perl

use strict;
use warnings;
use threads;
use MCE::Hobo;
use MCE::Shared;
use DBI;
use Data::Dump;
use feature qw(say);

use constant AMOUNT => 1;
use constant MAX    => 100;
use constant DB     => qq(dbi:SQLite:testomato.db);

say qq($0 $$);

sleep AMOUNT;

my $shared = MCE::Shared->array();

my $cores = MCE::Util::get_ncpu();

MCE::Hobo->init( max_workers => $cores );

for  my $id ( 1 .. MAX ) {
     my $hobo = MCE::Hobo->create( \&task );
     say qq( $id ) . $hobo -> pid();
}

MCE::Hobo->wait_all();

my $result = $shared->export;

dd $result;

sub task {
   my $db = DBI->connect( DB, "", "") or die DBI->errstr;
   my $result = $db->selectall_arrayref("SELECT * FROM fubar");
   $db -> disconnect;
   $shared -> push($result);
   sleep AMOUNT;
}

__END__
[download]

The flow can be nicely observed in the process table.

Here is how to generate the example db:

Karls-Mac-mini:db karl$ sqlite3 testomato.db "create table if not exis
+ts fubar(id INTEGER PRIMARY KEY, name TEXT,  surname TEXT);"
Karls-Mac-mini:db karl$ sqlite3 testomato.db "insert into fubar (name,
+ surname) values ('karl','goethebier');"
Karls-Mac-mini:db karl$ sqlite3 testomato.db "select * from fubar";
1|karl|goethebier
Karls-Mac-mini:db karl$
[download]

As i don't have Postgres on my box and i don't want it i used SQLite to show the basic idea. A database is a database. I don't know if this example is helpful. But i guess at least it might be interesting. Best regards.