Hi Panos,

Thank you for providing a code sample. I added user_begin and user_end options. In MCE, workers call user_begin and user_end one time (before and after running). Thus, reconnecting to the DB each time is not necessary.

e.g. { user_begin } { user_func chunk_1 } { user_func chunk_2 } ... { user_func chunk_N } { user_end }

#!/usr/bin/perl -w
use strict;

use MCE;
use DBD::Oracle;
use DBI;

sub myBegin {
    my ($mce) = @_;
    $mce->{db} = DBI->connect(
       "dbi:Oracle:<SERVER_NAME>", "<USERID>", "<PASSWORD>"
    ) || die($DBI::errstr . "\n");
    return;
}

sub myEnd {
    my ($mce) = @_;
    $mce->{db}->disconnect;
    return;
}

sub mySub {
    my ($mce, $chunk_ref, $chunk_id) = @_;
    my $db = $mce->{db};

    return;
}

my (@array, $mceObj, $db);

$db = DBI->connect(
   "dbi:Oracle:<SERVER_NAME>", "<USERID>", "<PASSWORD>"
) || die($DBI::errstr . "\n");

...do some work with the database in order to fill up
...the @array variable...

$db->disconnect;

$mceObj = MCE->new(max_workers => 4,
                   input_data => \@array,
                   user_begin => \&myBegin,
                   user_func => \&mySub,
                   user_end => \&myEnd);

$mceObj->run;
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From reading your code, am still not sure the reason for the ora_stmt_type redefined errors stated in the initial post. Connecting one time may solve the issue.