Fragment-and-Replicate Join Partitioning not possible for some join conditions e.g., non-equijoin conditions, such as r.A > s.B. For joins were partitioning is not applicable, parallelization can be accomplished by fragment and replicate technique Depicted on next slide Special case – asymmetric fragment-and-replicate: One of the relations, say r, is partitioned; any partitioning technique can be used. The other relation, s, is replicated across all the processors. Processor Pi then locally computes the join of ri with all of s using any join technique. General case: reduces the sizes of the relations at each processor. r is partitioned into n partitions,r0, r1, ..., r n-1;s is partitioned into m partitions, s0, s1, ..., sm-1. Any partitioning technique may be used. There must be at least m * n processors. Label the processors as P0,0, P0,1, ..., P0,m-1, P1,0, ..., Pn-1m-1. Pi,j computes the join of ri with sj. In ...
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