[Bioperl-l] Searching by source in Bio::DB::SeqFeature::Store?

[Sendu Bala]

Once I store a feature like so:

$db = Bio::DB::SeqFeature::Store->new( # mysql );
$db->new_feature(-primary_tag  => 'X',
                  -seq_id       => 'Y',
                  #...
		 -source       => 'Z');

How do I search for it again? I could have sworn that in the past the 
source somehow became one of the feature's attributes so that I could do:

@feats = $db->features(-attributes => {source => 'Z'});

(Or does/did some other feature-related module store source as an 
attribute, and in the past I stored those features in my db?)

The obvious isn't implemented:

@feats = $db->features(-source => 'Z');

Looking at the code I see I can do type and source at the same time:

@feats = $db->features(-type => 'X:Z');

which works, but how do I just search for all Z, regardless of type?