Subject Full joins...
Author Jonathan Neve

I've discovered to my dismay something that you all have probably known
for a long time: a left outer join only returns a record if the field
being joined on in the main table is non-null! (Feel free to correct me
if I've misunderstood something)

1) Why????
2) I found that a full join works... but it's unbearably slow!

Jonathan Neve.