Cartesian Product Join is a TYPE of Join
where as
Product Join is a Join Strategy chosen by the optimizer.
If you don't specify a join condition between two tables, it is a Cartesian Product Join type that you are specifying. The join strategy will be a Product join to perform this Cartesian Product Join.
But there are scenarios, where you specify proper join conditions. But optimizer thinks it is less resource consuming if the smaller table is duplicated over all the AMPs and performs a PRODUCT join. [This scenario may arise when the PI of the tables are not matching/covered by the Joining Columns and one table is very small as compared to the other table]
Hope this helps..
Thanks, Manish
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