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Exactly. Indeed, from what I recall from relational database theory, joins are usually treated as cartesian products (outer joins) which are then filtered by th

Exactly. Indeed, from what I recall from relational database theory, joins are usually treated as cartesian products (outer joins) which are then filtered by the join condition.

catnaroek 9y ago
An outer join a Cartesian product is not. Even if you stick to ordinary (inner) joins, they are pullbacks, not products. https://en.wikipedia.org/wiki/Pullback https://en.wikipedia.org/wiki/Pullback
- falcor84 9y ago
  D'oh, sorry, I meant "cross join"