// relational matching
create view Sunset as
select image from MyPhotos
where  title = 'Pittwater Sunset'
       and taken = '2012-01-01';
// similarity matching with threshold
create view SimilarSunsets as
select title, image
from   MyPhotos
where  (image ~~ (select * from Sunset)) < 0.05
order  by (image ~~ (select * from Sunset));