# get content-blob 
    foreach my $f ('XML', 'SGM')
    {  
        my $sql = "SELECT cnt_inhoud FROM content WHERE " .
                    "cnt_doc_id = '$id' " .
                    "AND  cnt_formaat = '$f'";

        my $sth = $dbh->prepare ($sql, { ora_auto_lob => 0}) ||
                                    confess "execute error: $DBI::errstr";

        $sth->execute () || return "Prepare error";
        ($locator) = $sth->fetchrow_array ();
        $sth->finish();
        $formaat = $f;
        last if (defined ($locator));
    }
   
    if (! defined ($locator))
    {  
        print STDERR "No *ML-blob present voor $id.\n" unless ($::silent);
        return ($this->errorstatus_nothing_found(), undef);
    }
   
    my $file = "$dir/$prefix$id.OUT";
    my $fh;
    if (! open ($fh, ">$file"))
    {  
        print STDERR "kan $file niet openen voor schrijven\n" unless($::silent);
        return ($this->errorstatus_blobdump_faalde(), undef);
    }
   
    print Dumper $dbh;
    print Dumper $locator;
    my $chunk_size = 1024 * 5;      # 5 K
    my $offset = 1;   # Offsets start at 1, not 0
	# THIS ora_lob_read call CAUSES THE ERROR MESSAGE
    while(my $data = $dbh->ora_lob_read ($locator, $offset, $chunk_size))
    {
        print $fh $data;
        $offset += $chunk_size;
    }

use strict;
use DBI;
use DBD::Oracle;

=cut

drop table content;
create table content (
  cnt_doc_id  integer primary key,
  cnt_formaat varchar2(3),
  cnt_inhoud  clob
  )
/
insert into content values (0,'XML',null);
insert into content values (1,'XML',empty_clob());
insert into content values (2,'XML','Michel Cadot');
commit;

=cut

print "Perl version: $^V\n";
print "DBI version: $DBI::VERSION\n";
print "DBD::Oracle version: $DBD::Oracle::VERSION\n";

my $dbh = DBI->connect ('dbi:Oracle:','michel','michel') 
 || ( print "execute error: $DBI::errstr\n" && exit 1);
print "Database version: " .
       ($dbh->selectrow_array
         ("select version from product_component_version where product like 'Oracle%'")) .
       "\n\n";

my $locator;
my $formaat;
my $sth;

for my $id (0,1,2) {
  print "id=$id\n";

    # get content-blob 
    foreach my $f ('XML') #, 'SGM')
    {  
        my $sql = "SELECT cnt_inhoud FROM content WHERE " .
                    "cnt_doc_id = '$id' " .
                    "AND  cnt_formaat = '$f'";

        $sth = $dbh->prepare ($sql, { ora_auto_lob => 0}) ||
                 ( print "prepare error: $DBI::errstr\n" && exit 1 );

        $sth->execute () || ( print "execute error: $DBI::errstr\n" && exit 1);
        ($locator) = $sth->fetchrow_array ();
        # $sth->finish();
        $formaat = $f;
        last if (defined ($locator));
    }
   
    if (! defined ($locator))
    {  
        print STDERR "No *ML-blob present voor $id.\n" ;
        next;
    }
   
    my $chunk_size = 1024 * 5;      # 5 K
    my $offset = 1;   # Offsets start at 1, not 0
# THIS ora_lob_read call CAUSES THE ERROR MESSAGE
    while(my $data = $dbh->ora_lob_read ($locator, $offset, $chunk_size))
    {
        # print $fh $data;
        print "$data\n";
        $offset += $chunk_size;
    }

$sth->finish();

}

exit 0;

E:\>perl test_lob.pl
Perl version: v5.20.2
DBI version: 1.633
DBD::Oracle version: 1.74
Database version: 11.2.0.4.0

id=0
No *ML-blob present voor 0.
id=1
id=2
Michel Cadot