Can you simply move the db before you start working on it, rendering it unavailable for when you do the transactions?:

use warnings;
use strict;

use File::Copy;

my $db = 'test.db';
my $disabled_db = 'test-locked.db';

move $db, $disabled_db or die $!;

# your code here, using $disabled_db in your connect

...
[download]

-stevieb