Monday, 2 December 2013

Blobs in Postgresql with Perl

Are you using, or do you want to use Postgresql Blobs with Perl?

Providing you are in the Moose ecosystem, here is Pg::Blobs. Pg::Blobs is a role that adds blobs handling methods to any Moose based package.

Here is how to use it:

package My::App;
use Moose;
with qw/Pg::Blobs/;
# Just provide:
sub pgblobs_dbh{ .. return the DBH .. }

Now your package My::App is capable of managing Postgresql blobs:

my $o = .. and instance of My::App ..
my $blob_id = $o->pgblobs_store_blob($binary_content);
print $o->pgblobs_fetch_blob($blob_id);

A couple of guidelines:

Blobs in Postgresql are just numeric Object IDs. You WILL have to store them in a OID column for later retrieval. If you don't, there is no guarantee they will persist, as any unreferenced blob can get vacuumed away.

You MUST wrap any blob operation in a transaction.

Happy blobing!