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Cartesian Join


Notes:

Cartesian joins are often the result of a missing predicate. For example, here I have forgotten the join condition:
select * from emp, dept where salary > 30000;
Beware of this situation.
But, this is not always the case. The slide contains a valid example – joining to a one-row average company salary table. The TKPROF excerpt shows the plan includes a “MERGE JOIN CARTESIAN”.