![]() ![]() In the algorithm, there are various terms used: It is the Hash join algorithm in which we have computed the natural join of two given relations r and s. Such that t s = t r įor each matching tuple t s in Hsi do begin Probe the hash index on Hsi to locate all tuples Read Hsi and build an in-memory hash index on it Perform the join operation on each partition// Therefore, in this way, the hash join operation works. We do not need to compare the b tuples in any other partition. Thus, we only compare a tuples in a i with b tuples of b i. It implies that tuple a should be in a i, and tuple b should be in b i. Suppose that both a and b tuples consist of a hash value as i. It means they have the same value for the join attributes. ![]() The main goal of using the hash function in the algorithm is to reduce the number of comparisons and increase the efficiency to complete the join operation on the relations.įor example, suppose there are two tuples a and b where both of them satisfy the join condition. The hash function provides the hash value. The partition is done on the basis of the same hash value on the join attributes. The concept behind the Hash join algorithm is to partition the tuples of each given relation into sets. The Hash Join algorithm is used to perform the natural join or equi join operations.
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