Data Distribution (cont)
Consider table R horizontally partitioned into R1, R2, ..., Rn
Fragmentation can be done in multiple ways, but need to ensure ...
Completeness
- decompostion is complete iff each t∈R is in some Ri
Reconstruction
- original R can be produced by some relational operation
Disjoint
- if item t ∈ Ri, then t ∉ Rk, k ≠ i (assuming no replication)
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