use strict;
use warnings;

use DBI;
require DBD::Oracle;

# Filename and field ID on the command line.
my ($filename, $dbid) = @ARGV;

my $dbh = DBI->connect("DBI:Oracle:host=your.hostname.here:sid=YOURDBNAME:port=8080", 
             'your_username',
             'your_password',
             {LongReadLen => 100_000_000, RaiseError => 1});

my $sth = $dbh->prepare("select your_blob_field from your_table where your_id_field=? for update", {ora_auto_lob => 0});

$sth->execute($dbid) or die($sth->errstr);
my $char_locator = $sth->fetchrow_array();
$sth->finish();

die("No record found") unless $char_locator;

open(my $fh, '<', $filename) or die("Error opening file: $!");

my $chunk_size = 4096;    # Arbitrary chunk size

# Write file to BLOB record.
my $offset = 1;    # Offsets start at 1, not 0
my $length = 0;
my $buffer = q{};
while( $length = read( $fh, $buffer, $chunk_size ) ) {
    $dbh->ora_lob_write( $char_locator, $offset, $buffer );
    $offset += $length;
}
close($fh);

# If the new BLOB in DB was smaller than the original, adjust the
# size of the BLOB field
if ( $offset < $dbh->ora_lob_length( $char_locator ) ) {
    $dbh->ora_lob_trim( $char_locator, $offset - 1 );
}

$dbh->disconnect();