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Reduce-side joins will be implemented via 1-Bucket-Theta as described in \[3\]. This requires the cardinality of the two relations and therefore to perform a reduce-side theta join statistics must be turned on. IfInitially if the required statistics do not exist an exception will be thrown indicating the problem. After the initial implementation we can use a method to estimate the cardinality.

As previously mention a detailed description of 1-Bucket-Theta is located \[3\]. As such the discussion of the internals of the algorithm will be brief. Joining two relations S and T can be viewed as a matrix with the S, the smaller relation, on the left and T on the right.